Along with the standard partitioning scheme supported by DOS, Windows 3.x, Windows 95/98/Me, and Windows NT, Windows 2000 supports a new dynamic disk system that provides greater versatility in disk management. The following sections describe the basic and dynamic disk systems and explain basic disk administration tasks.
Windows 2000 refers to disks using the partitioning schemes used in previous operating systems as basic disks. In this scheme, disks are divided into one or more partitions, each of which can contain volumes (units of storage accessible with a drive letter). The two basic partition types, primary and extended, are described in the sections that follow.
A primary partition is a bootable partition on a disk. Each disk can contain only one active primary partition, although partitions can be marked inactive. A primary partition contains a single volume, which can be formatted with the NTFS, FAT, or FAT32 filesystems.
An extended partition can only be created after the primary partition and typically uses the disk space unallocated to the primary partition. An extended partition is divided into one or more logical drives , each of which can be formatted as a volume.
Logical drives are not bootable. The Windows 2000 system partition (the partition containing NTLDR and other boot files in the root directory) cannot be located on a logical drive, but the boot partition (the partition containing the operating system files in the WINNT directory) can.
New to Windows 2000 is a system of dynamic disks, which can be used instead of the basic scheme. The dynamic disk system treats the entire hard disk as a single partition. This partition can be further divided into one or more volumes. Three types of volumes are available; these are described in the sections that follow.
A simple volume can use all or part of a single disk. Simple volumes are similar to volumes in the basic disk system, but can be resized dynamically without starting the computer. Simple volumes can be formatted with FAT, FAT32, or NTFS.
A spanned volume is a single volume that includes space on two or more physical disks. As many as 32 disks can be combined into a single volume. Windows 2000 writes data to the first disk in the spanned volume until it is full, then continues with the remaining disks. The loss of a single disk within a spanned volume will cause the loss of the entire volume. Spanned volumes may not be used for the system or boot partitions.
A striped volume combines several physical disks (2-32 disks) into a single volume, but makes a more efficient use of space. Data is stored in small sections (stripes) of each disk in turn, so that all disks maintain the same amount of free space.
The advantage of striping is speed; read or write requests can be distributed across several physical drives. However, as with a spanned volume, the loss of a single drive will cause the loss of all of the data on the volume. As with spanned volumes, striped volumes cannot be used for the system or boot partitions.
The Disk Management snap-in is Windows 2000’s main tool for disk administration. You can access this snap-in by adding it to a console or by accessing a console that already includes it, such as the Computer Management console. To access this console, select Programs → Administrative Tools → Computer Management → Storage → Disk Management from the Start menu.
The Computer Management console with the Disk Management snap-in selected is shown in Figure 3-6. The initial display shows a graphic representation of the disks in the system, each divided into its component partitions or volumes. Disks are labeled as basic or dynamic, and the system and boot partitions are labeled.
The following sections describe a number of basic disk management tasks using the Disk Management snap-in.
For basic disks, you can create a partition by right-clicking on the disk and selecting Create Partition. If a disk contains no partitions, you can also configure it as a dynamic disk. Right-click on a dynamic disk to create a volume.
After a basic partition or dynamic volume is created, right-click and select Format to configure it for a filesystem. This option is also available for existing volumes and will erase all data in the current volume.
For existing partitions, you can right-click on the partition and select Properties to display settings for the partition. This allows you to modify sharing, security, and quota options and provides access to troubleshooting tools.
To create a spanned volume, select an area of free disk space on a dynamic disk, right-click and select Create Volume. A spanned volume can also be extended with additional free space: select the volume and an area of free space, right-click, and select Extend Volume.
To create a striped volume, select an area of free disk space on a dynamic disk, right-click, and select Create Volume. This requires a minimum of two areas of free space on separate dynamic disks. A striped volume cannot be extended.
The Disk Management snap-in also provides a one-way method of converting basic disks to dynamic disks. To convert a disk, right-click the basic disk and select Upgrade to Dynamic Disk . This process preserves the data on the disk.
When a disk is upgraded, each primary partition or logical drive is converted to a simple volume on the dynamic disk; there is no longer any distinction between the partition types.
Volume sets and stripe sets, Windows NT 4.0’s equivalent of spanned and striped volumes, can be included in the upgrade. Volume sets are converted to spanned volumes, and stripe sets are converted to striped volumes. These are no longer accessible to NT 4.0.
As data is stored on disk, a file may be separated into one or more physical locations on the disk. For example, this happens when a volume has a number of small areas of free space and you write a large file to the disk. Although Windows 2000 has no trouble handling fragmented files, a large number of them can degrade performance.
The Disk Defragmenter snap-in, also included in the Computer Management console, allows you to analyze disk fragmentation and defragment disks as needed. Select a drive in the upper area of the window, then click Analyze to view a graph of the disk’s fragments or Defragment to defragment the disk.
Windows 2000 supports disk compression for specific files or folders on NTFS volumes. The files are stored in compressed form, but can be accessed like normal files; they are dynamically uncompressed automatically. This conserves disk storage, but requires more CPU time when files are being compressed or uncompressed.
To compress a file or folder, open its Properties dialog and click the Advanced button. The Advanced Attributes dialog includes a Compress contents to save disk space option; select this option to compress the file or folder. When you compress a folder, you are asked to choose whether to compress the folder only, or its contents, including files and subfolders.
File compression follows a set of inheritance rules when you move or copy files. The rules are as follows:
When a file or folder is copied from an NTFS folder to another NTFS folder, it inherits the compression settings of the destination folder.
When a file or folder is moved from an NTFS folder to another NTFS folder on the same volume, it keeps its current compression setting. If it is moved from one volume to another, it inherits the settings of the destination folder.
When a compressed file or folder is moved or copied to a FAT partition, it is uncompressed, because FAT does not support compression.
Windows 2000 includes a disk quota feature, which can be used to limit the disk storage consumed by each user. To set quotas for a disk, right-click on the disk in My Computer or Disk Management and select Properties, then select the Quota tab, as shown in Figure 3-7. The following options are included:
- Enable quota management
If selected, quotas are enabled for the disk.
- Deny disk space to users exceeding quota limit
If selected, users will be unable to write to the disk after exceeding their quota. Otherwise, quotas will be used strictly for monitoring purposes.
- Select the default quota limit
Select the default disk quota for users or select Do not limit disk usage to disable quotas by default; you can still add quotas for individual users or groups. You can also set a lower warning level.
- Select the quota logging options
Select whether an event is logged when a user exceeds the quota or when a user exceeds the warning level.
The Quota Entries button at the bottom of the dialog displays a separate window listing all quota entries. Select Quota → New Quota Entry to add an entry for an individual user or group.
Encrypted Filesystem (EFS) is a new Windows 2000 feature that uses public-key encryption to encrypt and decrypt files in folders. To encrypt a folder’s contents, select the General tab from the folder’s Properties dialog, then click Advanced. Select the Encrypt contents to secure data option to encrypt the folder.
Encryption is transparent to the user; files are automatically decrypted when accessed, provided the user has permission to access the file. To decrypt a folder permanently, deselect the Encrypt contents option in the Advanced Properties dialog.
Windows 2000 includes a new backup program, Windows Backup. This utility is available from the Accessories → System Tools menu under the Start menu or by running the NTBACKUP.EXE program directly.
The main Backup screen includes options for the Backup Wizard, which prompts you for information to back up files; the Restore Wizard, which prompts you for information to restore files; and an option to create an emergency repair disk (ERD). The following sections describe the advanced features of the program.
Select the Backup tab to display a full set of backup options, as displayed in Figure 3-8. This dialog displays a hierarchical listing of the contents of the computer’s disks. Select a drive, directory, or individual files to comprise the backup set.
You can also use Backup to back up the computer’s registry and boot files. To enable this feature, check the System State option in the Backup tab.
The destination for the backup can be duplicate files (on another disk or removable media) or a tape if a tape device has been installed. To change the backup type, select Options from the Tools menu. The following types of backup are allowed:
- Normal (full backup)
Backs up all of the files on the volume regardless of when files were modified and clears the archive bits (file attributes that indicate whether a file has changed since the last backup)
- Incremental backup
Backs up all of the files that have been modified since the last backup and clears the archive bits
- Differential backup
Backs up all of the files changed since the last full backup but does not clear the archive bits, so each differential backup includes the same files as a previous one
- Copy
Similar to a full backup, but does not clear the archive bits
- Daily copy
Backs up all files modified on the current date