Chapter 9
Backup Operations

Data backup involves transferring files from a system's primary storage to a different local or network device. Unlike simple file copying performed using the server operating system's file management system, backup programs (either those built into operating systems or purchased separately) perform file compression and, optionally, encryption during the backup. As a result, backed-up files must be restored before they can be used. Timely and well-organized data backups enable a business to recover from hardware failure, user error, or other threats to the contents of a server's hard disk.

While data backup is at least moderately important for individual PCs, it is a critical task for a server. Depending on the amount of new data generated and stored on a server, a weekly backup routine is often the absolute minimum recommended, and daily backups are often in order.

Backups provide additional benefits, as well. In addition to recording a copy of current information, backups can be used to move older and infrequently used data from hard disk to tape storage, giving the server's hard disk more capacity for newer and more frequently accessed information.

Historically, a popular method for backing up full hard disks or modified files has been using a tape backup drive. Although tape backups are no longer the only way to back up a server, tape backups remain the most popular method. This chapter discusses tape, removable-media drives such as Iomega REV drives, rewritable DVDs, and disk-to-disk backups to help you determine which type of storage technology is right for you.

This chapter examines the various types of tape and other backup drives on the market. It begins by looking at tape backup units, describing the capacities of different drives, the system requirements for installation and use of a tape drive, tape libraries, tape backup upgrades, backup strategies, and common backup applications.

Tape Backup Units

A tape backup drive is the most simple and efficient device for creating a full backup of a hard disk if the tape is large enough. With a tape backup drive installed in a computer, you insert a tape into the drive, start your backup software, and select the drive and files you want to back up. The backup software copies your selected files onto the tape while you attend to other business. Later, when you need to retrieve some or all of the files from the backup tape, you insert the tape in the drive, start your backup program, and select the files you want to restore. The tape backup drive takes care of the rest of the job.

Tape drives come in a variety of industry-standard as well as some proprietary formats. This chapter covers the major industry-standard formats:

• Travan—Travan is a development of the QIC and QIC-Wide family of low-cost, entry-level tape backup drives. Travan drives can handle data up to 40GB at 2:1 compression.
• DAT (digital audio tape)—This is a newer technology than QIC and its offshoots, and it uses digital data storage (DDS) technology to store data up to 72GB at 2:1 compression (DAT 72). DAT drives are often referred to as DDS drives for this reason.
• DLT (digital linear tape)—DLT drives use servo-based linear recording, writing one track the length of the tape, repositioning the head to a new track, and then writing another track as the tape is wound in the opposite direction.
• SDLT (Super DLT)—SDLT is a development of DLT designed to handle higher-capacity drives. It uses laser-guided magnetic recording (LGMR) to boost tape capacity and other technologies to improve capacity, speed, and reliability. Current SDLT drives can store up to 600GB (2:1 compression).
• Ultrium—Ultrium uses dual-servo tracks and a nonvolatile RAM (NVRAM) chip in each cartridge to enhance data reliability. Current LTO-3 drives store up to 800GB (2:1 compression).

Note

A servo track is a prewritten track that is used to ensure that data is written in a readable manner. Ultrium and several other types of tape backup technologies use servo tracks.

Most current tape drives and all tape libraries support LVD SCSI interfaces, although some also support USB, ATA/IDE, Narrow SCSI, and FireWire interfaces. The following sections provide details.

Travan

Travan is a family of quarter-inch tape drives and cartridges that 3M (now Imation) developed in 1994. Travan was designed to support backward compatibility with certain QIC and QIC-Wide tape cartridges and to boost capacity and reliability.

Note

QIC was the Quarter-Inch Cartridge Drive Standards, Inc., trade association, which developed standards for quarter-inch tape drives and media starting in the early 1980s. QIC-Wide was a Sony-developed technology that was based on QIC MC standards but used a wider (8mm) tape.

Although the QIC trade association became inactive in 1997, the QIC website is still online, at www.qic.org. The information provided there can be useful if you need to determine drive and media compatibility for QIC tape backups in your archives or need to retrieve files from a .qic backup file.

Travan drives, unlike larger tape backups, fit into a 3.5-inch form factor. Travan drives maintain backward compatibility with various QIC standards and provide backup capabilities up to 20GB uncompressed and 40GB at 2:1 compression. Table 9.1 provides a guide to the Travan family tree. Note that the only current versions of Travan are Travan 20 (NS-20, TR-5) and Travan 40 (TR-7).

Table 9.1 The Travan Family of Cartridges

Nonstandard versions of Travan technology included the 5GB Tecmar/Iomega DittoMax, 5GB Hewlett-Packard/Colorado, 6.6GB AIWA Bolt, 7GB Tecmar/Iomega DittoMax, 10GB Tecmar DittoMax, and 14GB Hewlett-Packard/Colorado. These drives are basically orphans and should be used only to recover archival data stored on media that cannot be read on a standard Travan drive.

Note

Backward compatibility can vary with drive; consult the manufacturer to verify backward compatibility issues before purchasing any drive.

Current Travan Drives and Media

Travan NS drives (Travan NS-8, Travan 20, and Travan 40) use a dual-head design that permits verification during the data writing process instead of requiring the user to rewind the tape and reread it for verification, as with older Travan, QIC, and QIC-Wide drives. Travan NS drives also use hardware-based data compression for faster backups instead of software-based data compression, as with older Travan products.

Travan 20 and 40 drives are currently available from Quantum, thanks to Quantum's 2005 acquisition of Certance (formerly Seagate Removable Storage Solutions LLC). Travan 40GB drives are available in internal ATA/IDE and external USB 2.0 form factors. Travan 20 drives are available in internal ATA/IDE and SCSI-2 and external USB 2.0 form factors.

Certance/Quantum model numbers include the following:

• CTM40, for Travan 40 media.
• CTM20, for Travan20 media.
• CTMCL, which is the cleaning cartridge model (this cartridge also works with Travan-8, NS-8, and Travan 20 drives).

Media is available from Quantum and from many other vendors, including Dell, IBM, Imation, Sony, and Seagate. Figure 9.1 illustrates a typical Travan 20 or Travan 40 data cartridge. Before backing up to this type of media, you need to make sure the cartridge's write-protect switch is open (unlocked) for recording. When you've completed a backup, you should close the write-protect switch to prevent accidental overwriting on a cartridge that contains archival data.

Figure 9.1 Setting a Travan 20 or 40 cartridge's write-protect switch.

Installing a Travan 20/40 Physical Drive

Travan 20 and 40 ATAPI (ATA/IDE) and SCSI-2 drives can be installed in a 3.5-inch or 5.25-inch drive bay. If a 5.25-inch drive bay is used, you use a mounting bracket kit like the one shown in Figure 9.2. The mounting bracket kit provides the large faceplate needed to completely cover the 5.25-inch drive bay opening and extends the sides of the drive so that the drive can be mounted in the larger drive bay. If the case uses drive rails, you attach them to the sides of the mounting bracket kit.

Figure 9.2 Installing a Travan 20 or 40 drive into a mounting bracket kit to permit installation in a 5.25-inch drive bay.

Travan 20 and 40 USB drives do not require special installation and can be connected to any USB 2.0 port. These drives can be used with USB 1.1 ports, but performance will be severely limited.

Configuration for Travan ATAPI Drives

Travan 20 and Travan 40 drives cannot be used on the same ATA/IDE cable as an ATA/IDE hard disk and should always be connected to a separate cable. However, the second cable can also host an ATAPI CD-ROM, DVD-ROM, or other removable-media ATAPI drive. By using a separate cable for the tape backup and hard disk drive, the tape backup can run at maximum speed and will not interfere with the hard disk during backup or restoration operations.

Although Travan 40 drives have four sets of jumpers on the rear of the drive (see Figure 9.3), only the rightmost two are used. You remove the jumper block to configure the drive as a slave when the drive is installed on the same cable as another ATAPI drive. You insert the jumper block into the rightmost set of jumpers to configure the drive as master. If an 80-wire Ultra ATA cable is used, you can insert the jumper into the Cable Select jumper one position to the left from the Master jumper.

Figure 9.3 Jumper selections for a Travan 40 ATAPI drive.

Travan 20 drives use the traditional three-position jumper (Master, Slave, Cable Select) used by most other ATA/IDE and ATAPI drives. The jumpers are mounted on the bottom of the drive rather than at the rear.

Configuring Travan 20 SCSI-2 Drives

Travan 20 SCSI-2 drives are designed to work on Narrow SCSI (50-pin) interfaces rather than the 68-pin LVD SCSI interfaces used by most SCSI-interface tape backups for servers. The drive uses a standard 50-pin SCSI-2 ribbon cable. The configuration jumper pins are located on the bottom of the drive. They permit the drive to be configured for any SCSI ID between 0 and 7 and are also used to enable or disable termination, provide termination power, and enable parity checking (see Figure 9.4).

Figure 9.4 SCSI configuration for a Travan 20 SCSI-2 tape backup drive. Note that the drive is upside-down in this view.

Termination power and parity checking are enabled by default. If another device on the SCSI daisy chain, such as a hard disk, is already configured to provide termination power, you need to disable the tape backup's termination power setting. If double bus termination power is present, backup problems can result. Parity checking should always be left enabled to ensure reliable backups; you should disable it only for diagnostic purposes.

If the drive is located at the end of the SCSI daisy-chain (that is, at the end of the cable), you insert the termination jumper. If the drive is located elsewhere in the daisy-chain, you remove the termination jumper.

Travan Software Drivers and Utility Programs

The Travan 20 and Travan 40 drives currently sold at retail include Yosemite TapeWare XE Server/Workstation backup software. This backup program supports the following server operating systems for ATAPI drives: Windows NT 4.0, Windows 2000 Server, Windows Server 2003, and Linux for ATAPI drives; and Windows 2000 Server and Windows Server 2003 for USB drives.

For third-party backup software support, you should go to the software vendor's website or use the Quantum compatibility guide that is available at www.quantum.com/ServiceandSupport/CompatibilityGuides/Index.aspx.

If you plan to use Travan 40 ATAPI drives with the built-in backup programs in Windows NT 4 or in Windows 2000 Server/Windows Server 2003, you can download drivers from www.quantum.com/ServiceandSupport/SoftwareandDocumentationDownloads/Travan40ATAPI/Index.aspx. These versions of Windows have native support for Travan 20.

TapeRX diagnostics for Travan 20 and Travan 40 drives are available for Windows, Linux, NetWare, and Solaris, from www.quantum.com/ServiceandSupport/SoftwareandDocumentationDownloads/Travan40USB2.0/Index.aspx.

DDS-3, DDS-4, and DAT72 Tape Drives

Of the many high-performance] tape drives on the market, a great choice for use with entry-level to midrange servers is the DAT/DDS tape drive family because of its combination of performance, capacity, reliability, and reasonable price. Current members of the DDS family include the following:

• DDS-3 (DAT 24)—DDS-3 has a slightly larger capacity (12GB native/24GB at 2:1 compression) than Travan 20. SCSI-2 versions are read/write compatible with DDS-1 (1.3/2.6GB for 60 minutes or 2.0/4.0GB for 90-minute tapes) and DDS-2 (4.0/8.0GB) media. SCSI-2 versions are sold by Quantum, Hewlett-Packard, IBM, and Dell. External USB 2.0 versions, sold only by Hewlett-Packard, are read/write compatible with DDS-2 media.
• DDS-4 (DAT 40)—DDS-4 has a 20GB native/40GB at 2:1 compression capacity, which is double the capacity of Travan 20 and equal to Travan GB. It is read/write compatible with DDS-3 media. Quantum DDS-4 drives use the Ultra 2 SCSI LVD interface, while Hewlett-Packard DDS-4 drives use the SCSI-2 interface. Both are available in internal and external form factors. Hewlett-Packard also produces USB 2.0 drives in both internal and external form factors.
• DAT 72—The newest member of the DAT/DDS family, DAT 72 drives have a 36GB native/72GB at 2:1 compression capacity. They are read/write compatible with DDS-4 and DDS-3 media.

Note

Some DDS-4 drives are also read compatible with DDS-2 media, which means they can be used in place of older drives for retrieving existing backups. Some DDS-4 drives are also read/write compatible with DDS-2 media, which means they can reuse DDS-2 media. It's important to check media compatibility with the drive manufacturer for details.

DDS and DAT 72 drives use helical scan recording. The read/write heads used in helical scan recording are mounted on a drum and write data at a slight angle to the tape, using a mechanism highly reminiscent of that in a VCR. The entire surface of the tape is used to store data, enabling more data to be placed in a given length of tape than with the linear recording techniques that the QIC and Travan family of drives use.

Table 9.2 lists current DDS-3, DDS-4, and DAT 72 drives, interfaces, and form factors, by manufacturer. Vendors such as IBM and Dell are not listed; they do not manufacture DDS and DAT drives but instead re-label drives from other vendors. Sony, the originator of the DDS standard, no longer makes DDS drives.

Table 9.2 Interfaces and Form Factors for DDS-3, DDS-4, and DAT 72 Drives

In 2006 and 2007, the next generation of DAT/DDS, DAT 160 (80GB native/160GB 2:1 compression) should be released. For a complete road map of DAT/DDS technology, visit the DAT Manufacturers Group website, at www.datmgm.com.

Quantum and Hewlett-Packard-Specific DDS/DAT 72 Features

Quantum's DDS-3, DDS-4, and DAT 72 drives feature a combination of technologies called TapeShield that are designed to protect drives and data:

• A sealed chamber for the head-to-tape interface
• A continuous-contact capstan cleaner
• A sapphire media-cleaning blade that removes debris from the tape before it contaminates the drive

These improvements enable DAT 72 drives to run 10 times longer in dusty conditions than similar drives that don't have these features. DDS-3, DDS-4, and DAT 72 drives from Quantum also feature SmartShield, which uses multiple reads to improve data recovery when reading from out-of-spec or weak recorded tapes.

Hewlett-Packard's DAT 72 drives include self-cleaning features and One Button Disaster Recovery, an easy-to-use disaster-recovery feature designed to restore a system to its most recent backed-up condition with the press of a button. This feature is supported on several Hewlett-Packard ProLiant servers. See http://h18006.www1.hp.com/products/storageworks/drs/index.html for compatibility information and technical notes.

DDS and DAT 72 Media

DDS and DAT 72 media is labeled with one of the logos shown in Figure 9.5. Current drive manufacturers recommend (of course!) their own brand of media. If you prefer a third-party brand, you need to make sure it supports the appropriate DDS or DAT level.

Figure 9.5 DDS and DAT 72 logos. When used on media, the DDS logo (top) is accompanied by a number that lists the DDS version (middle).

Even though DAT/DDS drives are more expensive than Travan drives with similar capacities, the drive's design is such that the cost of media is lower. For example, a DDS-4 data cartridge is about US$10 in single quantities, compared to about US$50 for a typical Travan 40 data cartridge in single quantifies. A DAT 72 cartridge is about US$23 in single quantities. Over time, a DDS-4 or DAT 72 drive is far less expensive to operate than a Travan 40 drive because of the sharply lower media cost.

Configuring and Installing a Quantum DDS/DAT 72 Tape Backup

Quantum DDS-3, DDS-4, and DAT 72 SCSI drives are designed to work with many different server operating systems, not just Windows. Consequently, installation and configuration of these drives is much more complex than with a Travan drive.

Before installing any drive, you need to install the software drivers provided with the drive. If additional software is needed, you should download it from the support page for the drive. You can download drivers for Windows, Linux, and other operating systems; TapeRX diagnostics; and firmware updates. To download these files, you select the drive type from the Quantum Software and Documentation Downloads page, at www.quantum.com/ServiceandSupport/SoftwareandDocumentationDownloads/index.aspx.

A Quantum DDS or DAT 72 internal SCSI drive has several sets of jumpers or DIP switches:

• The SCSI device ID jumpers are usually located at the rear of an internal drive. Quantum drives use a default SCSI ID of 6.
• Jumpers for enabling or disabling parity and termination power are usually located next to the SCSI device ID jumpers.
• DIP switches for advanced settings, such as data compression, operating system compatibility, SCSI Wide or Narrow, and others, are located at the bottom of the drive.

You configure external drives in the following ways:

• You configure SCSI device IDs by using a switch on the rear of the drive. A small window shows the current device ID. You press buttons above and below the window to select a different device ID. Quantum drives use a default SCSI ID of 6, and Hewlett-Packard drives use a default SCSI ID of 3.
• DIP switches for advanced settings, such as data compression, operating system compatibility, SCSI Wide or Narrow, and others, are located at the bottom of the drive under a small access panel.

Figures 9.6 and 9.7 show examples of these jumpers and switches.

Figure 9.6 The default SCSI Device ID, parity checking, and termination power jumper settings for Quantum internal DDS-4 and DAT 72 drives.

Figure 9.7 Default settings for advanced tape drive configuration DIP switches on Quantum internal and external DDS-4 and DAT 72 drives.

Note

Depending on the drive, documentation for a Quantum DDS or DAT 72 drive might be labeled Seagate, Certance, or Quantum. Seagate was the original manufacturer of most of these drives, before it spun off its tape drive division as Certance. Quantum then purchased Certance in 2005.

Generally, DIP switches 1 through 4 and 9 should be left in their default ON position. However, depending on the server operating system you use, you might need to adjust the position of DIP switches 5 through 8 and 10. The default ON setting shown in Figure 9.7 configures these drives to support Windows NT 4.0, Windows 2000 Server, Windows 2003 Server, Windows 98, Windows Me, and Windows XP.

Table 9.3 lists the appropriate configurations for other operating systems.

Table 9.3 Operating System–Specific DIP Switch Settings for Quantum DDS-4 and DAT 72 Internal SCSI Tape Backup Drives

Internal DDS-3 drives use a 10-position DIP switch on the underside of the drive for SCSI ID and other configuration settings. The SCSI ID can also be configured with DIP switches on the rear of the drive. For details, see http://downloads.quantum.com/Certance/manuals/userguides/user_guide_stdx24000n_en.pdf.

You use external terminators with Quantum internal SCSI tape backups if the drive is at the end of the SCSI daisy-chain. Quantum internal drives fit into half-height 5.25-inch drive bays. All external SCSI tape backups from any vendor require termination if the drive is at the end of the SCSI daisy-chain.

Configuring and Installing a Hewlett-Packard DDS or DAT 72 Tape Backup Drive

Hewlett-Packard provides a CD containing its StorageWorks Library and Tape Tools with its drives. If the CD contains drivers for your operating system, you should install the appropriate drivers. If a driver for your operating system is not supplied with the drive, you can download updates from the Hewlett-Packard website. To determine software compatibility with a particular Hewlett-Packard tape backup drive, you can go to www.hp.com/go/connect, click Tape Backup, and then click Software Compatibility. Next, you click the entry for each combination of drive and operating system for compatibility details and links to driver updates. Unlike Quantum's SCSI DDS and DAT 72 drives, which depend on a combination of software drivers and DIP switches to configure a drive for a particular operating system, Hewlett-Packard tape drives use software drivers.

To configure the SCSI Device ID on an internal drive, you use the jumper blocks on the rear of the drive. Hewlett-Packard SCSI tape drives are generally configured using Device ID 3; if you need to change the default ID, refer to Table 7.6 in Chapter 7, "The SCSI Bus." The jumpers used to configure the device ID are numbered 1 through 4, from right to left. Other jumpers should not be moved from their default locations. You configure external drives using push buttons to select SCSI IDs. Hewlett-Packard DDS-3 drives support SCSI IDs 0 through 7; Hewlett-Packard DDS-4 and DAT 72 drives use a Wide SCSI interface and support SCSI IDs 0 through 15.

Figure 9.8 illustrates the location of the SCSI ID jumper blocks and external switch on a Hewlett-Packard DDS-3, DDS-4, or DAT 72 drive.

Figure 9.8 Configuring the SCSI ID on an Hewlett-Packard internal (left) and external (right) tape drive.

You use external terminators with Hewlett-Packard SCSI tape backups if the drive is at the end of the SCSI daisy-chain. Hewlett-Packard internal drives fit into half-height 5.25-inch drive bays.

To install a Hewlett-Packard USB 2.0 drive, you connect the drive to a USB 2.0 port built into the server or an add-on card. For best performance, you should not connect the drive to a USB 2.0 hub.

DLT and SDLT

Digital linear tape (DLT) technology was originally developed by Digital Equipment Corporation (DEC) in 1991. DEC sold its DLT business to Quantum in 1994, and since then, DLT and its higher-capacity sibling, Super DLT (SDLT), have become some of the leading high-end tape backup technologies. Both DLT and SDLT drives are manufactured and sold by many vendors, including ADIC, Hewlett-Packard, IBM, Overland Storage, Quantum, and Tandberg Data.

DLT segments the tape into parallel horizontal tracks and records data by streaming the tape across a single stationary head at 100 inches to 150 inches per second during read/write operations. This is in dramatic contrast to traditional helical-scan technology used by DDS and DAT 72 drives, in which the data is recorded in diagonal stripes, with a rotating drumhead, while a much slower tape motor draws the media past the recording head.

The result is a very durable drive and a robust medium. DLT drive heads have a minimum life expectancy of 15,000 hours under worst-case temperature and humidity conditions. DLTtape III has a life expectancy of 500,000 passes, and DLTtape IIIXT and DLTtape IV double the life expectancy to 1 million passes.

SDLT uses several technologies to increase capacity and reliability over those of the already-impressive DLT standards. These include laser-guided magnetic recording (LGMR), a pivoting optical servo on the backside of the media, thin-film magneto-resistive cluster heads for tape reading and writing, high-efficiency PRML channels for greater recording density, improved media coating, and a positive engagement tape-leading buckling mechanism.

SDLT drives can read SDLT and DLT media up to six generations back. This enables you to replace older, smaller drives with newer, larger drives without losing access to older backups.

Note

SDLT and DLT media use different head cleaning cartridges because of the differences in recording head and media technologies between DLT and SDLT.

Current DLT and SDLT Drives and Media

Although DLT drives have previously been available in capacities as low as 10GB native/20GB at 2:1 compression (DLT-2000), the smallest-capacity DLT drive currently on the market is the DLT VS80, which has a capacity of 40GB/80GB (2:1 compression). Table 9.4 lists the specifications for current DLT and SDLT drives. All current DLT and SDLT drives are designed to connect to Wide SCSI (68-pin) interfaces.

Table 9.4 Current DLT and SDLT Drives

DLT media is available in three families: DLTtape III, DLTtape IIIXT, and DLTtape IV. Current installations of DLT drives are most likely to support DLTtape IV. This media can also be read by SDLT drives. SDLT media is available in two families: Super DLTtape I (SDLTtape I) and Super DLTtape II (SDLTtape II). Table 9.5 lists the specifications for DLT and SDLT media.

Table 9.5 DLT and SDLT Media

Configuring and Installing DLT and SDLT Drives

Compared to DDS and DAT72 /tape drives, the configuration of current DLT and SDLT drives is relatively simple. The software drivers used by DLT and SDLT drives are used to optimize these drives' operations with different operating systems rather than the configuration jumpers used by DDS and DAT72 tape drives. The only hardware setting used by current DLT and SDLT tape drives is the SCSI device ID. For internal drives, you use jumper blocks on the rear of the drive to configure the SCSI device ID. For external drives, you use push buttons to set the device ID. Figure 9.9 illustrates typical DLT drives, the Quantum DLT VS80 in its external and internal versions, and the SCSI device ID settings used on these drives. For other drives, see the documentation.

Figure 9.9 Rear views of the Quantum DLT VS80 external (top) and internal (bottom) tape drives.

As with any SCSI drive, if a tape drive is the last drive in the daisy-chain, it must be terminated. With external drives, you connect an external terminator to the second connector on the drive (refer to Figure 9.9). To terminate an internal drive, you connect the terminator/to the data cable connector at the next position past the drive.

LTO Ultrium

LTO Ultrium is the highest-performing and highest-capacity open standard tape backup system currently available for servers. Ultrium was developed by the Linear Tape-Open (LTO) Technology organization, co-founded by Hewlett-Packard, Seagate, and IBM in 1997. Originally, LTO developed two standards: Ultrium (optimized for high capacity) and Accelis (optimized for high speed). Accelis was never adopted, in large measure because Ultrium provided comparable speeds at higher capacities. Thus, Ultrium and LTO are sometimes used interchangeably. The first Ultrium drives (LTO-1) were released in 2000. Currently, LTO-1, LTO-2, and LTO-3 drives are available from many vendors, including Hewlett-Packard, IBM, Quantum, and Tandberg Data.

Note

To learn more about Ultrium and LTO, visit the LTO Technology organization website, at www.lto.org

LTO Ultrium technology divides a 384-track half-inch tape into four data bands, separated by servo bands. Each read/write head contains eight elements. Two servo bands are used simultaneously to provide accurate head positioning and to overcome any flaws in the media. Tape is written bidirectionally at very high speeds. Each data band is written in the opposite direction from the previous band to help avoid cross-talk between data bands.

Each Ultrium cartridge contains a NVRAM chip that provides calibration and other information. The drive reads this information and uses it to help operate the cartridge in an optimal manner. This information can also be read by an RF receiver before the cartridge is inserted into a tape drive. As with other current tape backup technologies, Ultrium uses the read-while-write method of data verification. If data cannot be verified, it is rewritten on another portion of the tape during backup.

LTO Ultrium Drives and Media

Ultrium products are currently available in three generations: LTO-1, LTO-2, and LTO-3. Each generation doubles the native and 2:1 compressed capacity compared to the previous generation, and each generation also significantly increases the compressed transfer rate. Table 9.6 lists current Ultrium drives from major vendors.

Note

Full-height LTO drives offer faster performance than half-height versions.

Table 9.7 lists the specifications for each LTO Ultrium standard. As this table indicates, LTO-3 drives are read/write compatible with LTO-2 media and can read LTO-1 media. LTO-2 drives are read/write compatible with LTO-1 media. As LTO continues to be developed, forthcoming drives are expected to continue to feature read/write compatibility with the previous generation and read compatibility two generations back. Backward compatibility makes it easier to move up to higher-capacity drives without the necessity to convert existing backup data to a new drive format.

Table 9.7 LTO Ultrium Specifications

Configuring and Installing LTO Ultrium Drives

As with DLT and SDLT drives, configuring LTO Ultrium SCSI drives is relatively simple. With external drives, you use push buttons to set the device ID. With internal drives, you use jumper blocks on the rear of the drive to configure the SCSI device ID (see Figure 9.9 for examples of both types of drives). See the drive's documentation for specific jumper configurations.

If a drive is the last drive in the daisy-chain, it must be terminated. With external drives, you connect an external terminator to the second connector on the drive. To terminate an internal drive, you connect the terminator to the data cable connector at the next position past the drive.

Before connecting a drive to your system, you should install the drivers included with the drive. You can visit the vendor's support site to download updated drivers.

Tape Autoloaders

If tape capacity had kept pace with hard disk capacity, it would be easy to make backups: You could just install a single blank tape in the tape backup and start the process. Then you could label it when you're finished and put it aside for storage. However, in many cases today, a single backup requires multiple tapes:

• Even entry-level servers today might use large ATA/IDE or SATA hard disks that range in capacity from 100GB to as much as 500GB. SCSI and SAS hard disks are now available in 300GB sizes. Most tape backups discussed in this chapter have capacities smaller than these extremes, even when a 2:1 compression ratio is assumed.
• Multidisk SCSI or SATA RAID arrays might have capacities approaching the terabyte (1,000GB) range, which exceeds even the capacity of LTO-3 Ultrium tape backups (800GB at 2:1 compression).

To avoid the need to manually load tapes for a multiple-tape backup, you can consider a tape autoloader. An autoloader is an external device that contains a single tape backup drive and holds anywhere from 8 to 16 tape cartridges. When the first cartridge is full, the autoloader removes it and inserts another. The process is repeated until the backup task is finished. Tape autoloaders are available in DDS/DAT, DLT, SDLT, and LTO-Ultrium formats. Most vendors that sell individual tape drives also sell autoloaders, and autoloaders are also manufactured by companies that incorporate third-party tape drives. Figure 9.10 illustrates a typical autoloader for DLT cartridges.

Figure 9.10 A typical 8-slot autoloader for DLT cartridges.

Autoloader Drives and Media

Table 9.8 lists the specifications for the most common autoloaders based on the drives covered earlier in this chapter.

Table 9.8 Autoloaders Based on DDS/DAT, DLT, SDLT, and LTO Technologies

The media used by an autoloader is the same as that used by a single tape drive, using the same technology. Autoloaders have trays or cassettes that hold the media when not in use. To simplify calculation of native and compressed capacities, you should use the same size and type of media for each cartridge, even if the drive can read and write to more than one size of media.

Installing Autoloaders

Many autoloaders are designed and configured for rack installation. A 2U-sized rack is normally used. A team of two people should work together to install the unit into a rack: one to hold the unit, and the other to fasten the unit to a rack. Some autoloaders are designed to work in a full-height 5.25-inch drive bay, and others can be placed on a desktop.

Most autoloaders use Ultra160 SCSI interfaces, but some are available in 2Gbps Fibre Channel interfaces as well. For best performance, autoloaders as well as single tape backup drives should be connected to a separate SCSI channel from SCSI drives or RAID arrays.

If the vendor recommends it, you should connect the autoloader to a slot-based SCSI host adapter rather than to a SCSI RAID or integrated SCSI host adapter. If necessary, you should install the recommended SCSI host adapter into the server before continuing. You need to be sure to terminate the autoloader if it is the last (or only) device on the SCSI bus. Generally, this requires that you attach the appropriate type of terminator to the unused SCSI connector on the rear of the autoloader.

When you fill the autoloader's magazine with data cartridges, you need to make sure each cartridge is not write-protected. Some autoloaders require you to insert the cartridges one at a time. Others use multicartridge inserts. If the unit is a dual-capacity 8/16 cartridge unit, you must use a magazine blank and a single eight-cartridge magazine or else two magazines of eight cartridges each.

The front panel is used to perform most initial setup and management tasks. Depending on the autoloader, typical options might include the following:

• The SCSI device ID for the drive
• The SCSI device ID for the autoloader (if it requires its own device ID)
• Date/time and time zone information
• Cartridge changing mode
• Cleaning tape location and settings
• Which magazine to use (on dual-magazine units)
• Passwords and security settings
• Installation of system updates
• Other device-specific settings, such as network configuration and compression

Even if you plan to use remote network management for an autoloader, you must first configure devices that support remote management with the appropriate IP address and other network configuration settings.

Some autoloaders, particularly those made for DAT 72 and DDS-4 media, might require you to configure the drive with DIP switches and a back panel option switch if you plan to use a Linux or other non-Windows operating system with the autoloader. Typically, the default setting supports Windows operating systems.

If the autoloader includes a web-based management interface, you need to connect an RJ-45 cable from your network to the RJ-45 (Ethernet) port on the rear of the autoloader. After you use the front panel to configure the autoloader, you can log in to the autoloader's IP address and perform most of the management tasks you can also perform through the device's front panel controls. Some of the tasks you will find particularly useful to perform remotely include cartridge inventory, cleaning the drive (if a cleaning cartridge is installed), moving a cartridge, viewing drive usage statistics, running diagnostic tests, and configuring a single IP address or range of IP addresses authorized to manage the drive. Note that autoloaders can also be configured to work in an Auto Clean mode if a cleaning cartridge is installed.

Autoloader Troubleshooting

Autoloaders are a good bit more complex than single tape backup units. To troubleshoot a unit, you use the front-panel display or remote management. If the device stores log files, you should examine them, which typically requires you to log in to the unit remotely. If the vendor provides diagnostic software, you should run it to determine problems. Note that the diagnostic software provided with the unit might not be compatible with some operating systems. You can visit the vendor's website for the latest versions.

You need to verify that the autoloader works with your tape backup application. For some backup software, whether built in to the operating system or provided by a third party, you might need to install patches or updates to enable it to work with an autoloader. You can check the autoloader vendor's website for compatibility information and links to update files.

You need to be sure to check SCSI-specific settings, such as device IDs (each device on a particular SCSI bus must have a unique SCSI ID), cabling, and termination.

You also need to check the signal lights on the front of the unit, which are used to report various problems. The patterns of flashing lights or, on some units, the color of the LED, are used to indicate various problems. You should see your unit's documentation for details.

If the drive is not using the latest firmware and you are having problems, you should update the firmware.

Tape Libraries and Enterprise Units

As the previous section discusses, tape autoloaders enable you to automate tape backup and archiving to handle the backup requirements of large hard disks. However, if you are responsible for an enterprise-level server, an autoloader might not provide enough capacity or sufficient management options to be suitable. In such cases, you should consider a tape library.

A tape library resembles an autoloader, but with the following differences:

• Number of drives—An autoloader has only one drive, whereas a tape library usually has two or more drives. Some enterprise-level tape libraries sold by IBM, for example, support up to 192 drives.
• Number of cartridges—Entry-level tape libraries usually support 24 or more slots for data or other cartridges. Some enterprise-level tape libraries can support more than 500 slots.
• Library partitioning—A library can be partitioned into two or more logical libraries. Each library can be used as a virtual backup destination or source for a different server or department.
• Expandability—Most tape libraries are modular, enabling multiple modules to be managed as a single logical unit.
• Manageability—Tape libraries are designed for remote network management.
• Support for Fibre Channel–based storage area networks (SANs) as well as SCSI interfacing—Fibre Channel is a high-speed (up to 4Gbps) connection between servers and shared storage devices such as tape drives and libraries. Fibre Channel can use optical fiber, coaxial cable, and UTP cable.
• Availability of a mail slot—A mail slot is a special slot that does not require that all cartridge be re-inventoried when the cartridge is added to or removed from this slot. The mail slot is a good location to use for the cleaning cartridge.

Tape libraries are normally based on the largest and fastest tape backups available in a particular technology. These are the most common choices:

• LTO Ultrium (LTO-2 and LTO-3)
• SDLT (SDLT 600 and SDLT 320)

Some tape libraries support only one type of drive, but others support mixing LTO Ultrium and SDLT drives in the same unit. This is useful because LTO-3 Ultrium and SDLT 600 media are now available in a special write-once, read-many (WORM) format. Thus, you could partition a tape library could to write data for permanent archiving to the drive using WORM tape media and data for backup and later reuse and replacement to the library's other drive, using standard rewritable tape.

Installing Tape Libraries

Tape libraries usually require some assembly. You might need to install the entry/exit port (used to move cartridges), support legs, and a conversion kit to convert a tabletop unit into a rack-mounted unit. Some libraries also require you to install the tape drives and to add additional power supplies for redundancy or to provide necessary power for a larger number of tape drives.

Tape libraries, unlike tape autoloaders, usually include one or more onboard SCSI host adapters in a mini-PCI form factor. The SCSI host adapter is used to run the library's robot tape loading/unloading/movement mechanism. If the tape library will be partitioned into two or more logical libraries, additional SCSI host adapters are needed in the library (see Figure 9.11).

Figure 9.11 A tape library configured as four logical libraries.

Depending on the size of the tape library, one host adapter might be used to run one or more drives. Each tape drive in a tape library, as well as the library itself, requires a SCSI device ID. For example, a tape library with two tape drives requires three unique SCSI device IDs. Special short patch cables are used for daisy-chaining SCSI drives to each other.

You use the front panel to configure the SCSI device IDs, other SCSI settings (mode, bus parity, and so forth), Fibre Channel options, library partitioning, reserved slot(s) for cleaning cartridges, TCP/IP network settings, front panel and media security locks, and magazine access (for loading or removing cartridges). You also use the front panel for viewing and changing system settings such as cartridge access mode, automatic cleaning, cartridge mapping (displays cartridge names), emulation (necessary to enable some backup programs to operate with certain libraries), and library maintenance (rebooting, updating firmware, and so forth). If a tape library is connected to a Fibre Channel switch, one cable from the switch is connected to the library, and a separate cable from the switch is connected to each drive built in to the tape library.

To permit remote management, you connect an RJ-45 Ethernet port in the tape library to an RJ-45 cable from your network. To manage the tape library via a web browser, you enter the IP address assigned to the unit and provide a password to log in to the unit. You can normally perform most configuration options through the web browser.

To create a library partition, you must specify which SCSI or Fibre Channel host adapter card will control access and specify which tape cartridge slots and drives are assigned to that partition.

A tape library requires at least one and sometimes more AC power cords. You need to be sure to provide an AC outlet with adequate power to run the tape library.

Tape Library Troubleshooting

Learning to troubleshoot a tape library requires that you familiarize yourself with the methods your library server uses for reporting problems. The front-panel LCD display is often used to display problem messages and error codes, for example. If you use remote access, you should check the documentation to determine whether some problems are only reported through the front-panel LCD display. Before you can control the robot remotely, you might need to configure it for remote access.

Cartridges are identified by unique bar codes. If the system is unable to locate a particular cartridge, you should check the bar code labels on each cartridge. Any labels that are worn or dirty should be replaced. If the labels are clean, you need to make sure the laser and lens used to read the bar code is not dirty or blocked by debris. You can use the bar code statistics readout to determine failure rates.

You can use other reports to find additional problems. On the first sign of a problem, you should try resetting the library. If problems recur, you should contact the company for help.

Alternatives to Tape Backup

Although tape backup has long been the leading solution for backing up servers, it might not be appropriate for your situation, particularly if you have a relatively small server hard disk or don't require automation. The following sections discuss the leading alternatives to tape backup:

• Disk-to-disk backup
• Iomega REV
• DVD-rewritable

After discussing these alternatives, we take a look at the limitations of these methods.

Disk-to-Disk (D2D) Backup

As an alternative to tape backup, many users of desktop PCs and entry-level servers now use some form of D2D backup. The most common type of D2D backup involves the use of an external IEEE 1394 or USB 2.0–based hard disk equipped with backup software. "One button" backup drives can start the backup program automatically as soon as the drive is plugged in to the system and powered up.

For drives with relatively small amounts of changing data to back up, a low-end D2D backup using an external hard disk makes a great deal of sense. External hard disks are now available with capacities as high as 500GB. External drives with capacities of 300GB or larger are big enough to permit a full backup and many incremental backups of a typical 160GB entry-level server hard disk.

Unlike tape backups, which require that the tape be advanced to a particular point before a restore process can begin, restorations from a D2D backup can begin instantaneously.

D2D backup is not limited to USB 2.0 or IEEE 1394 drives, however. Network-based backup appliances are available for backing up multiple stations on a network. In addition to traditional backup programs that can also be used in a D2D backup process, special D2D software is now available from several sources.

IBM introduced Tivoli Continuous Data Protection (CDP) for Files in 2005 for Windows 2000 Server, Windows XP, and Windows Server 2003. CDP backs up changed files to a variety of local and network drives in real-time and periodically backs up data to a remote file server or Tivoli Storage Manager. For more information, see www-306.ibm.com/software/tivoli/products/continuous-data-protection/. Microsoft also released System Center Data Protection Manager (DPM) D2D program in 2005. DPM supports Windows Server 2003 on servers or NAS storage devices. DPM tracks and stores byte-level changes to server files and offers scheduled replication. For more information, see www.microsoft.com/windowsserversystem/dpm/default.mspx. Traditional backup programs are also available in D2D versions.

For more information about D2D backup programs, see "Third-Party Backup Software," p. 551.

High-end disk-based backup devices that emulate tape libraries are also available. These devices enable a backup to be performed directly to a large hard disk array. Later, backup files can be transferred to tape for archiving operations, enabling the backup drive to be reused.

Iomega REV

Although current tape technologies such as LTO, SDLT, and DAT 72 are much faster than their predecessors, tape drives are still hampered by their linear technology that requires sequential access to data. To find a particular area of a tape to use for backup or restoration, you must move the tape past the recording head. Even though some recent tape technologies store certain information about a particular cartridge in the cartridge's NVRAM, it still takes time to rewind the tape and advance it to a particular location.

If only certain files need to be restored, the user must wait as the tape is advanced to the first file, the file is read and restored to disk, the tape is advanced to the next file, and so forth. To replace outdated files on a tape, the tape must be rewritten.

In contrast, removable-media storage provides random, rather than sequential, access to files and easy replacement, when necessary, of outdated information. However, traditional removable-media storage such as Zip, rewritable CD, and even rewritable DVD do not have capacities comparable to even entry-level server hard disks.

Iomega's REV removable-media drive is designed to provide capacity comparable to that of DAT 72 or DLT VS80 tape drives while providing faster read and write access. REV uses 35GB hard-disk-type removable-media cartridges that Iomega refers to as removable rigid disks (RRDs). Unlike older technologies such as Zip, REV's RRD cartridges provide a sealed, air-filtered environment for read/write heads and electronics. The RRD media in a REV cartridge spins at 4,200RPM. While this is significantly slower than desktop ATA/IDE hard disks, this spin rate is comparable to that of many laptop ATA/IDE hard disks. In drag-and-drop file transfer tests, REV drives offer comparable transfer rates to 30GB ATA/IDE hard disks with files up to 64KB in size, and they are much faster with files of 1MB or larger. The maximum data transfer is up to 25MBps.

Iomega REV Capacity

The native capacity of any Iomega REV drive is 35GB. Iomega claims a maximum compressed capacity of 90GB (2.6:1), based on testing performed with the Calgary Corpus data set. However, most users will not see this level of data compression in most real-world operations. The reason is that the files used in the Calgary Corpus were primarily text files. As any time spent using PKZip, WinZip, or the built-in Zip-compatible Windows XP archiving feature will tell you, text files can be compressed up to 90% smaller than normal. However, a great deal of the data on today's systems is already compressed data, such as JPEG photos, PDF files, MP3 and WMA audio files, zip and cab archives, and so forth. A better estimate for compression performance is to assume a maximum capacity of 70GB (2:1 compression), as is assumed by most third-party backup products.

Note

The Calgary Corpus data set was developed in 1990 by Tim Bell and Ian Witten. It can be downloaded from www.data-compression.info/Corpora/CalgaryCorpus/.

A newer data set used for compression testing is the Canterbury Corpus. It can be downloaded from http://corpus.canterbury.ac.nz/index.html. This corpus was developed in 1997. You might want to try both with your favorite backup or archiving programs to see how the results differ.

Iomega REV Drives

Iomega offers a wide variety of drive interfaces for REV, enabling you to choose a drive for almost any type of internal or external host adapter. Table 9.9 lists available models. Note that all drives include Iomega Automatic Backup Pro for Windows 2000 and XP.

Table 9.9 Iomega REV Drive Versions

REV is supported by many third-party server backup applications. To determine whether you need updates, you can visit your backup application vendor's website. Some vendors offer bundles including REV drives, media, and a backup application. Note that the NT Backup utility that is built in to Windows 2000 Server and Windows Server 2003 cannot span a backup to multiple REV cartridges unless Firestreamer-RM is installed.

See the tip on p. 543 for details on using Firestreamer-RM to span a backup to multiple rewritable DVDs.

Note

For users of larger hard disks who need an autoloader, REV is also available in a 10-cartridge autoloader format. The REV Autoloader 1000 is a desktop device with a native capacity of 350GB and a compressed capacity of 700GB (2:1 compression). It includes CA BrightStor ARCServe Backup OEM edition for a single server, and it connects to a server via a 68-pin LVD SCSI connection. Options include a bar code reader, a remote management unit, and 2U rack-mounted hardware.

DVD Rewritable/Recordable

If you need to perform backup on a budget, you can use a rewritable DVD drive. Usually, dual-layer (DL) rewritable DVD drives can be substituted for DVD-ROM or rewritable CD drives when a server is first configured, or they can be added later. The native capacity of single-layer DVD media is 4.7GB. If you use DL media, each disc can hold 8.5GB.

DVD rewritable media is a good choice for backups of work-in-progress because the media can be erased and rewritten later. Conversely, DVD recordable provides durable archival storage. Most server backup programs designed for small and medium businesses support DVD rewritable/recordable drives. Note that the NT Backup utility that is built in to Windows 2000 Server and Windows Server 2003 cannot span a backup to multiple rewritable DVDs or CDs unless Firestreamer-RM is installed.

See the tip on p. 543 for details on using Firestreamer-RM to span a backup to multiple rewritable DVDs.

Limitations of Tape Alternatives

Tape alternatives have some limitations compared to tape backups, including the following:

• The problem of creating a long-term backup archive—If you use D2D backups, you can back up your server quickly, but you should move the backups to archival tape media at some point. Thus, you should not look upon D2D as a total replacement for tape. If you use an external USB 2.0 or IEEE 1394a hard disk as a low-cost D2D backup for an entry-level server, you will eventually run out of disk space unless you move the backup files to other media such as DVD. To determine whether this is feasible, you should look at the backup files created on the external drive to see if they are small enough to move to DVD (4.7GB or less for standard DVD; 8.5GB for DL DVD).
• Capacity limitations—If you need to back up a large hard disk or RAID array, a network-based D2D backup solution can be more expensive than some autoloaders. The Iomega REV is most comparable to tape, but its capacity is roughly that of DAT 72. It would take several REV cartridges to back up a 160GB or larger drive on an entry-level or midrange server. If you use DVD media, it will take quite a few DVDs to back up even an entry-level server's 40GB or 80GB hard disk. Unlike tape or Iomega REV, DVD backups cannot be automated; you must insert each additional DVD disc after the previous one is filled.
• Software support—Although D2D, REV, and rewritable DVD drives are supported by many third-party backup utilities, you might need to upgrade your current backup program to obtain support for new types of hardware. You should be sure to check compatibility with your existing backup software before adding tape alternatives or switching from tape.

Tip

The Firestreamer-RM program adds support for rewritable DVD media, Iomega REV, and other types of removable-media drives to the NT Backup program used by Windows 2000 Server and Windows Server 2003 (including x64 and IA-64 versions); it also works with Windows XP. Firestreamer-RM supports volume shadow copy (enabling backups of open files), compression and data encryption, media and drive spanning, remote media via iSCSI, Microsoft Automated System Recovery, and other features. For more information and a free trial, go to the Cristalink Limited website, at www.firestreamer.com/Default.asp.

Upgrading Tape Backup Units

You can upgrade a tape backup drives (or tape alternative) to fix problems with the operation or performance in three ways:

• Driver upgrades
• Firmware updates
• Hardware upgrades

The following sections discuss these methods.

Driver Upgrades

Even though most tape backup drives (except for so-called bare drives) include a CD or DVD that contains drivers for major operating systems, you should go to the drive vendor's website and check for updates even before you install the driver CD or DVD. This is a good idea for several reasons:

• If you are using a recently released operating system or service pack, the drivers included with the backup unit might not support your software. You should download and install updates if necessary.
• Even if the installation media supports your operating system, there might be bugs or shortcomings in the version supplied with the backup unit. The latest versions on the website should be used in place of older versions.
• Diagnostic utilities on the installation media might also have been replaced with newer versions, or they might not support your particular operating system. However, the website often has the drivers needed for less-common server operating systems.

Tip

Don't forget to check for backup software updates, even if you use the backup software supplied with some tape or tape alternative backup drives. As with the drivers, there might be better versions available.

Firmware Updates

Just as firmware updates improve a server's ability to work with newer processors and memory and to correct various other problems, firmware updates can also solve problems for users of tape backup drives and other backup hardware.

A backup hardware vendor's website has the latest firmware updates. Note that firmware updates are customized to the particular server operating system in use. For example, if you need to update the firmware for a tape backup, an autoloader, or a library connected to a Linux server, you should make sure you download and install the Linux version of the firmware.

You should not install any firmware update unless it solves specific problems that you have with your system. If a firmware update fails, your drive or other backup device must be serviced.

Hardware Upgrades

Hardware upgrades can help improve the performance of your tape backup or other backup device. This does not always mean an upgrade to the backup device itself. For example, upgrading to a faster SCSI host adapter in the server (for example, Ultra320 rather than Ultra160) can improve performance for many midrange and high-end tape backups, autoloaders, and libraries.

Most SCSI-based tape backups and autoloaders recommend, if not require, that the backup device be on a separate bus from other SCSI devices. If you're using the same SCSI bus to run the tape backup and other SCSI devices (such as the server drive), adding an additional SCSI host adapter (Ultra160 or Ultra320, in most cases) for use by the tape backup will boost performance even more.

If you use a tape autoloader that can handle 16 cartridges, but you only use 8, adding the additional hardware needed to handle another 8 cartridges can help make backups easier. With more cartridges online, you won't need to change them as often. You should upgrade the tape drive for faster and higher-capacity backups. If the autoloader didn't include a bar code reader initially, you should add one for easier organization of large backup sets.

A tape library upgrade can include installation of additional SCSI host adapters to partition the library into multiple logical libraries, replacing SCSI with Fibre Channel, and swapping slower, lower-capacity tape drives for faster, higher-capacity drives.

To find out what the upgrade options are for a particular tape drive, autoloader, or library, you should check the vendor's website for technical documents.

Backup Operations

No matter what type of tape or tape alternative you choose for server backups, you need to understand how backup and restoration processes work and what can go wrong during either process. Typically, backup processes involve making a full backup, followed by one of various backup types that record only changes to files. For the greatest reliability, you should verify a backup upon completion. It's important to keep in mind that a backup must be restored before the files it contains can be used, although in most cases you have the option of restoring all files in a backup or ones that you select.

A successful backup involves the following steps:

1. Choosing a backup solution that supports your operating system and backup hardware.
2. Installing or configuring options for open file backup, client backup, and other options to maximize the ability to recover from data loss.
3. Selecting a full backup as the first backup operation you perform on the server. Make a backup copy, if needed, in case of disaster.
4. Verifying the backup.
5. Safely storing your disaster recovery backup for future use.
6. Performing differential or incremental backups on a regular basis. Differential backups are recommended because a smaller amount of media must be restored to recover from a system crash.
7. Rotating and replacing tape or removable-media cartridges to enable permanent storage of the most valuable data and prevent media failure and consequent data loss.
8. Cleaning the tape drive when recommended by the vendor.
9. Testing the ability to restore the backup. Ideally, you should attempt to restore a disaster recovery backup to a duplicate server. However, at the very least, you should attempt to restore selected files to another folder on your hard disk.

The following sections provide additional details regarding the backup process.

Backup Strategies

The term backup strategy refers to the decisions you make about subjects such as the following:

• What files to back up
• What method to use to back them up
• How often files should be backed up
• What to do about open files

The following sections discuss backup strategies, helping you to choose the best backup strategies for your network.

Full Backups and Disaster Recovery Backups

A full backup records all information on the server's hard disk, including data files, applications, operating system files, and the system registry or other configuration details (often referred to as the system state). A full backup should be performed as soon as a server is first configured into operating condition. With Windows 2003 Server, the option in Windows NT Server backup option All Information on This Computer sets up a full backup.

When a full backup is performed, many backup programs provide the option to create a disaster recovery backup. A disaster recovery backup usually involves the creation of one or more bootable floppy disks or a bootable CD. The bootable media is used to start the restoration process without the need to reinstall an operating system first.

Windows 2003 Server's integrated NT Backup utility includes a form of disaster recovery known as the Automated System Recovery (ASR) Wizard. ASR can be used to restore a working system from local storage. ASR makes a floppy disk that is used to guide the restoration process in conjunction with the original Windows 2003 Server CD. Note that ASR restores only system files needed to restart the system. Application and data files must be restored separately, unless you specified the Back Up All Information On My Computer option when you ran the ASR backup.

When a file or folder is first created, its archive bit (one of several file/folder attributes) is turned on. After a full backup, the archive bit is cleared (turned off). Understanding the role of the archive bit is essential to understanding the differences between other types of backups.

Differential Backups

It is not necessary to create a full backup every time you back up your system. Instead, you should back up only changed files. One method offered by most backup programs is a differential backup. A differential backup backs up all files that have changed since the last full backup was performed. Files that are newly created or have been changed turn on the archive bit, but a differential backup, unlike a full backup, does not clear the archive bit.

On a server that experiences many newly created or changed files, differential backups can take almost as much time as full backups. However, unlike incremental backups (discussed in the next section), only the last differential backup needs to be restored after a full backup is restored to restore a system to its latest backed-up configuration.

For example, assume that a server required 4 tapes for its initial full backup. The first differential backup might require only one tape, but because archive bits aren't changed, each differential backup is likely to take more media. However, even if the last differential backup required 7 tapes, the total number of tapes required to restore the backup would only be 11 (4 from the full backup plus 7 from the last differential backup). In most cases, you use fewer tape cartridges to restore your system to its last backed-up state with a differential backup because you only need to restore the full backup plus the last differential backup.

Incremental Backups

The other major method used for changed-file-only backups after a full backup is performed is the incremental backup. In an incremental backup, only files changed since the last full or incremental backup are stored. When a file is backed up using the incremental method, the archive bit set when the file was first created or was edited is cleared.

Incremental backups are much quicker to perform and require fewer tape cartridges or other media than differential backups. However, to restore a system to operation after a system crash, you must restore both the full backup and then all incremental backups made in the meantime. For example, assume that a full backup required two tape cartridges, and each incremental backup (performed weekly) required one backup cartridge. If the server crashed after a three-month period, you would need to restore about 16 tapes: 4 from the initial full backup and 12 (1 per week) incremental backup tapes, in order from oldest to newest. Even if each incremental backup used only part of a tape, that's a lot of media to restore.

Open File Backups

Open files create a major problem for reliable server backup. In recent times, servers are frequently running around the clock, 24/7, to provide access to files at any time, day or night. Thus, instead of there being several hours of inactivity during which all data files could be closed, backups are often performed while a server is providing data to some users.

Traditional backup programs cannot back up open files, meaning that the most important (or most used) files might not be backed up at all. To make certain that important files are backed up, server backup programs often include or can be upgraded with open file backup features. If your current backup program does not include or cannot be upgraded with open file backup, you should consider upgrading to a version that does support open file backup, especially if you must run backup while users are accessing files.

One method of performing open file backup is the Volume Shadow Copy Service (VSS) included in Windows 2003 Server.

Volume Shadow Copy Service (Snapshots)

Windows 2003 Server includes VSS as a method of backing up open files. VSS also protects files from accidental deletion or replacement on network shares.

VSS is supported on NTFS volumes only. It is enabled through a drive's properties menu. You click the Shadow Copies tab to enable or configure VSS for a particular drive. You can store VSS copies on the same drive letter or, preferably, a different drive letter.

The drive used for shadow copies must have at least 100MB of free space. You can limit the space used for shadow copies, but keep in mind that Windows 2003 Server can maintain up to 64 versions of each file. If you are not concerned about disk space, you should not limit the size of the shadow copy storage area. Windows deletes the oldest files if space becomes limited.

After a server has VSS enabled, you must install the Windows shadow copy client, which is available in the System32 wclientx86 folder located in the server's system (Windows or WinNT) folder. This client will work with Windows XP Professional. For Windows XP Professional and Windows 2000 clients, you can obtain a shadow copy client from www.microsoft.com/windowsserver2003/downloads/shadowcopyclient.mspx. You must use Windows Installer 2.0 or later to install the client.

After the client has been installed, a new tab called Previous Versions shows up in the properties sheet for network shared folders and files stored in folders on volumes running VSS.

To retrieve deleted files, you go to the network shared folder, open it, right-click an empty area, select Properties, and click the Previous Versions tab. Then you select the version and copy or drag it to the user's PC.

To retrieve a previous version of a corrupted or overwritten file, you right-click the file, select Properties, click Previous Versions, and select Restore (to replace current version) or Copy. If you select Copy, you need to choose a location for the file.

To recover a deleted folder, you open the folder that contained the deleted folder, right-click an empty area in that folder, select Properties, and click Previous Versions. Then you choose Copy to copy the folder and all contents to a location you specify. Next, you click Restore to recover the folder and all contents to the current folder.

If you use NTBackup as your server's backup utility, you need to run NTBackup from the command line to enable or disable backup of volume shadow copies. To enable backup of volume shadow copies, you use ntbackup/SNAP: on; to disable volume shadow copy backup, you use ntbackup/snap: off.

Deciding Which Backup Methods to Use

As you can see from the previous sections, a full backup is not the only backup method you should depend on. You should supplement a full backup with some type of changed-file backups, and, for extra security, implement volume shadow copies if you use Windows 2003 Server. For most users, a combination of full and differential backups produces the easiest type of backup to manage and restore.

One easy method for combining full with differential backups is known as the grandfather, father, son (GFS) method. GFS assumes daily backups on a weekly cycle. Before starting GFS, you should have a full backup. Then you create daily differential backups Monday through Friday and a new full backup on Saturday. The daily differential backups are known as the son, and the weekly full backup is the father. You repeat this weekly. The full backup on the last Saturday of the month (the grandfather) is considered a monthly backup and should be placed into permanent storage. You replace its media with new media.

Verification and Restoration

A backup of any type is worthless if it can't be restored. To make sure a backup can be restored, you should use verification. Modern tape backup systems covered earlier in this chapter perform read-after-write verification to make sure that data can be read immediately after it is written to tape. If a particular file cannot be read, the drive will write it again.

File Verification in Backup Programs

Note that read-after-write verification is not supported on D2D or removable-media backups. In such cases, you should select the option to verify data after backup in your backup application. You might want to use this option the first time you run a tape backup as well to assure yourself that the backup is valid.

With tape backup, the verify after backup option rewinds the tape to the beginning and compares each backed-up file to the file on the source drive, using some type of checksum comparison. If more than one tape was used for the backup, the first tape must be inserted, followed by each subsequent tape. If multiple removable-media or DVD discs are used, the first cartridge or disc must be inserted when prompted, followed by each subsequent cartridge or disc. D2D backups are the fastest and easiest to verify because the backup media does not need to be rewound or inserted.

If you see errors during verification, you should note which files caused the error. If the files were open during backup, you need to enable open file backup with third-party backup software or volume shadow copy backup with Windows 2003 Server and NTBackup. If the file was not open but could not be verified, you might have problems with the source drive or with your media. In that case, you should schedule a disk check with the option to fix file system errors and repair bad sectors. Then you should rerun the backup process and specify backup of only files that did not verify. If problems persist after disk checking, you should clean the tape drive and try a different brand of media.

Restoring Files from a Backup

If a file is damaged, overwritten, or deleted, you can restore it from backup media. You start the backup program and select the option to restore specified files. To ensure that you are restoring the latest version of a data file, you start the restoration process from the latest backup set. Normally, the backup program stores a catalog of each backup. However, if the backup catalog is lost, it can usually be re-created from the backup media.

After the catalog is retrieved or re-created for the latest backup, you need to locate the file(s) to be restored and select them for restoration. The backup device will locate the files, and the backup program will write the files back to their original locations. If you are restoring a good file to replace a damaged or incorrect file, you will be prompted to permit the replacement.

Restoring a Crashed Server Using Disaster Recovery

If you need to restore a crashed server, the easiest way to restore it is if you made a disaster recovery backup. Most modern backup programs support disaster recovery, which creates a full backup of the system and bootable media, enabling a "bare metal" recovery of the system to an empty hard disk. Depending on the backup program, a disaster recovery backup might be based on an image backup or a file-by-file backup.

You use the bootable CD or DVD you created to start the process. You insert your backup media when prompted until the system has been restored. Then you restore your daily backups. If you used the differential method, you need to restore only the last differential backup.

Restoring a Crashed Server Using ASR

If you used the ASR feature with Windows 2003 Server and need to restore from an ASR backup, you start the system with the Windows 2003 Server CD. When you see the prompt Press F2 to Run Automated System Recovery, you press the F2 key. Then you insert the ASR floppy disk. The system drive (usually the C: drive) is formatted by ASR. Afterward, a file copy process begins to restore a basic working copy of Windows 2003 Server. After the system reboots, the ASR Wizard starts and asks you where the ASR backup is located. After you specify the location, ASR restores information from your backup to your system drive.

After ASR is finished, you should restore other backups needed to complete the restoration of your system (such as the last full backup of non-system drives plus the most recent differential backup, or all incremental backups).

Restoring a Crashed Server Without Disaster Recovery or ASR

If you need to restore a crashed server without disaster recovery or ASR, follow this process:

1. Partition and format the drive where you plan to reinstall the operating system.
2. Reinstall the operating system.
3. Reinstall the backup software.
4. Restore the most recent full backup.
5. Restore the most recent differential backup or all incremental backups.

As you can see, it's much easier and faster to take advantage of disaster recovery backups, or, at the very least, ASR backups, than to restore a system from scratch.

Hardware Compatibility

A full system backup, including disaster recovery and ASR backup, is designed to be restored back to the same system. If you are restoring a backup due to hard disk failure, you should make sure the replacement hard disk is the same type and size, or larger, than the original. The rest of the hardware is the same as before, so the backup will be restored to identical hardware.

It's a bit tougher if you must replace a failed server. In such cases, you should use a server that's the same model or, for white box built-it-yourself servers, use a server with the same motherboard, video card, and other add-on cards. If you use hardware with different specifications, the restoration might fail, or the system might not be bootable afterward.

Backup and Restoration Troubleshooting and Documentation

If you are having problems with backing up or restoring data, you need to first identify your problem from the following sections and then follow the steps for the solutions they provide.

Backup or Restore Operation Failure

If your tape drive suffers a backup or restore operation failure, follow these steps:

1. Make sure you are using the correct type of tape cartridge.
2. Remove and replace the cartridge.
3. Restart the system.
4. Retension the tape.
5. Try a new tape.
6. Clean the tape heads.
7. Make sure all cables are securely connected.
8. Rerun the confidence test that checks data transfer speed with a blank tape. (This test overwrites any data that is already on the tape.)

Bad Block or Other Types of Media Errors

To troubleshoot bad block or other types of media errors, follow these steps:

1. Retension the tape.
2. Clean the heads.
3. Try a new tape.
4. Restart the system.
5. Try initializing the tape.
6. Perform a secure erase on the tape. (Previous data will no longer be retrievable from the tape.)

System Lockup or Freeze While Running Tape Backup

If your system locks up or freezes while running a tape backup, follow these steps:

1. Ensure that your system meets at least the minimum requirements for both the tape drive and the backup software.
2. For ATA/IDE (ATAPI) tape drives, make sure the tape drive is using a different host adapter than the hard disk. Set the CD or DVD drive to master and the tape drive to slave if both are using the same ATA/IDE port.
3. For SCSI tape drives, check device IDs, particularly if a new SCSI device has been installed since the last time the tape drive was used. Note that most vendors recommend that the tape drive be on a separate bus from the system's SCSI hard disk or SCSI RAID array.
4. Check the BIOS boot sequence; ensure that it is not set to ATAPI (tape/CD-ROM) devices if the tape drive is configured as a master device or as a slave with no master.
5. Make sure the hard drive has sufficient free space; most backup programs temporarily use hard drive space as a buffer for data transfer.
6. Hard drive problems can cause the backup software to lock up. Check your hard disk for errors by using CHKDSK or a comparable utility.
7. Check for viruses.
8. Check for previous tape drive installations; ensure that any drivers from previous installations are removed.
9. Restart the server in VGA mode. If the problem does not recur, contact your graphics board manufacturer for an updated video driver.
10. Disable antivirus programs and Advanced Power Management.
11. Try the tape drive on another computer system and different operating system, or try swapping the drive, card, and cable with known-good, working equipment. Start by swapping the cables.

Other Tape Drive Problems

The following are some other issues that might cause problems in general with tape backups:

• Corrupted data or ID information on the tape.
• Incorrect BIOS (CMOS) settings.
• Networking problems (outdated network drivers and so on).
• A tape that was recorded by another tape drive. If the other drive can still read the tape, this might indicate a head-alignment problem or an incompatible environment.

If you use a third-party backup program with disaster recovery enabled, make sure the boot floppies or boot CD-ROM are clearly labeled with the date and system name. If possible, store them with the media used to create the disaster recovery backup.

If you use ASR, make sure the date and system name are marked clearly on the ASR floppy. If possible, store the floppy with the media used to create the ASR backup.

Common Backup Software Applications

Backup applications abound, both those built in to server operating systems and those available from third parties. The following sections help you find the right backup software for your network.

Native Operating System Software

Most server operating systems include some type of backup software designed to support tape backup drives:

• Windows NT 4.0, Windows 2000 Server, and Windows Server 2003: NTBackup—NTBackup for Windows Server 2003 can be used to restore data backed up with NTBackup for Windows 2000 Server. NTBackup can be run in a wizard mode, an advanced mode, or a command-line mode.
• Linux and UNIX: tar—tar is a command-line utility that supports backups to tape drives as well as to archive files on a hard disk (see www.unixpress.com/cactus/lonetar/lonetar.html).
• Novell Netware 4.x and 5.x: SBackup and Enhanced SBackup—Some 4.x versions of NetWare include the sbackup.nlm (Netware Loadable Module), while later versions of 4.x and NetWare 5.x use Enhanced SBackup (SBCON).

Although many servers use integrated backup software, the desire for enhanced features such as support of autoloaders, tape libraries, and newer backup hardware and better disaster recovery options have led to the development of many third-party alternatives.

Third-Party Backup Software

The following are some of the leading third-party backup and disaster recovery programs for major server operating systems:

• BrightStor ARCserve Backup (Computer Associates)—This is a family of backup products for Windows and Linux servers and clients. It supports optional agents for disaster recovery, Windows and NetWare open files, tape libraries, SANs, tape RAID, image backup, online backups, and other functions.
• Lone-TAR (Lone Star Software Corporation)—Lone-TAR is a replacement for the UNIX and Linux tar command, offering menus, bit-level verification, and other advanced features. Companion products offer disaster recovery (Rescue-Ranger) and a graphical user interface (LTX).
• NovaNet (NovaStor Corporation)—NovaNet is designed to support cross-platform (Windows, Linux, NetWare) server and client backups. It supports plug-ins that provide open file management, disaster recovery, cluster and SQL server backups, and other services.
• Retrospect (EMC Dantz)—Retrospect 7 is a family of backup applications for Windows servers. Various versions support client backup and D2D backup, among others. Add-ons provide for open file backup, disaster recovery, support for tape autoloaders and libraries, and support for SQL Server or Exchange Server installations.
• Symantec LiveState Recovery (Symantec)—LiveState Recovery is a family of applications designed to support disaster recovery to Windows or other types of servers and desktops.
• Veritas Backup Exec (Symantec)—Backup Exec is a family of server backup applications for Windows servers. It supports D2D as well as tape backup, web-based file retrieval, and remote backup of Linux and UNIX servers, and there is a version that provides continuous protection for Windows servers.

Troubleshooting Backup Programs

The wrong time to discover that there's a problem with your tape backup system is when it fails. The following sections can help you solve problems in advance.

Backup Product Compatibility

Make sure that the backup software you use is designed to be compatible with your server (and client) operating systems, your backup hardware, and, if possible, your existing backups.

Some backup products are designed exclusively for Windows. Others support a mixture of Windows, Linux, and NetWare servers. In some cases, you can use remote agents to back up non-Windows servers using the backup device connected to the Windows server. While this enables you to standardize on a single backup program, it can increase network traffic significantly.

If you use Microsoft Exchange Server or SQL Server, consider backup programs or add-ons made especially for those server services. Many standard server backup programs are not optimized to back up those servers.

If network clients often store critical data on their local hard disks, consider a backup program that is designed to back up clients as well as servers. This is a built-in feature of some backup programs, but it is an extra-cost option in others.

From the standpoint of hardware, most commercial backup programs support tape drives and leading removable-media and DVD drives. It might be necessary to download updates to assure support. However, if you want to use an autoloader, a tape library, or a D2D backup device, you might need to purchase an extra-cost agent, plug-in, or update from your backup software vendor. When you consider the cost of your backup software, be sure to calculate the cost of any add-ons needed to support your hardware or network configuration.

If you upgrade to a newer version of the same vendor's backup software, you should be able to retrieve your existing backups with the new software version. However, don't assume that you can do so. Ask before upgrading.

Tip

Backup software vendor NovaStor (www.novastor.com) offers unique solutions for issues caused by moving from an older backup system to a new one: What to do with the data on the older tapes? NovaStor's TapeCopy 2.1 software enables you to move data archives from your outmoded SCSI, ATA/IDE, USB, or FireWire tape backup to a new tape drive or library. You can also use it to make hard disk copies of your tapes and to duplicate a backup tape on a similar drive. If you need to move data to a different operating system, NovaXchange provides cross-platform data transfer between different types of tape drives and libraries, operating systems, and architectures. See the website for details.

Backup Software Patches and Updates

Be sure to visit your backup software vendor's website to find the latest patches and updates for your backup software. If you use the backup software that is integrated in the operating system, visit your operating system vendor's website.