In this chapter, you will learn how to

From the standpoint of your PC, a freshly installed hard drive is nothing more than a huge pile of unorganized storage space. Sure, CMOS recognizes it as a drive—always a step in the right direction—but your operating system is clueless without more information. Your operating system must organize that storage so you can use the drive to store data. This chapter covers that process.

Historical/Conceptual

After you’ve successfully installed a hard drive, you must perform two more steps to translate a drive’s raw media into something the system can use: partitioning and formatting. Partitioning is the process of electronically subdividing a physical drive into one or more units called partitions. After partitioning, you must format the drive. Formatting installs a file system onto the drive that organizes each partition in such a way that the operating system can store files and folders on the drive. Several types of file systems are used by Windows. This chapter will go through them after covering partitioning.

The process of partitioning and formatting a drive is one of the few areas remaining on the software side of PC assembly that requires you to perform a series of fairly complex manual steps. The CompTIA A+ 220-1102 exam tests your knowledge of what these processes do to make the drive work, as well as the steps needed to partition and format hard drives in Windows.

This chapter continues the exploration of hard drive installation by explaining the concepts of partitioning and formatting, and then going through the process of partitioning and formatting hard drives. The chapter wraps with a discussion on hard drive maintenance and troubleshooting issues, the scope of which includes all the operating systems covered on the current exams.

■ Hard Drive Partitions

Before a magnetic disk drive leaves the factory, it is magnetically preset with millions (hundreds of millions on really big drives) of storage areas known as sectors. Older hard drives had 512-byte sectors; modern drives use 4096-byte Advanced Format (AF) sectors. Figure 9.1 shows a close-up of several sectors on a typical HDD.

• Figure 9.1 Sectors on an HDD

Solid-state drives come from the factory with each NAND chip storing millions (hundreds of millions on really big drives) of 4096-byte storage areas known as pages. A group of pages are combined into a block. The size of a block varies, but 128 pages per block isn’t uncommon. Figure 9.2 shows a simplified concept of how this looks.

• Figure 9.2 SSD pages and blocks

The CPU and operating system never talk to these internal structures. Instead, the controller on the HDD or SSD uses logical block addressing (LBA) to present all these storage chunks as nothing more than a number that starts at LBA0 and goes until every sector or page has an LBA number (see Figure 9.3). These LBA chunks are also called blocks.

• Figure 9.3 LBA in action

LBA makes addressing any form of mass storage easy, and that’s how the operating system interacts with the mass storage, via blocks. The operating system presents to the user files and folders, not LBA addresses. We must organize mass storage in a way that enables us to store and retrieve files, create folders, and so on. The first step to doing this is partitioning.

If you think of a hard drive as an empty building filled with many rooms (the blocks), partitioning is what organizes the rooms into something bigger (like suites or companies) and gives each bigger entity a name (see Figure 9.4). Partitioning takes a single physical drive and electronically organizes it into one or more . . . partitions. With that analogy, think of partitions as collections of rooms in the building. Partitions provide tremendous flexibility in hard drive organization. With partitions, you can organize a drive to suit your personal taste.

• Figure 9.4 Partitions on an SSD

You can partition a hard drive to store more than one operating system: store one OS in one partition and create additional partitions for another OS. Granted, most people use only one OS, but if you want the option to boot to either Windows or Linux, partitions are the key.

1102

Windows supports three different partitioning methods: the older master boot record (MBR) partitioning scheme, Windows’ proprietary dynamic storage partitioning scheme, and the GUID partition table (GPT). (I’ll cover all three of these in their respective sections, following this introduction.) Microsoft calls a hard drive that uses either the MBR partitioning scheme or the GPT partitioning scheme a basic disk and calls a drive that uses the dynamic storage partitioning scheme a dynamic disk.

A single Windows system with three hard drives may have one of the drives partitioned with MBR, another with GPT, and the third set up as a dynamic disk, and the system will run perfectly well. The bottom line? You get to learn about three totally different types of partitioning. I’ll also cover a few other partition types, such as hidden partitions, and tell you when you can and should make your partitions.

Master Boot Record

The first sector of an MBR hard drive contains the master boot record (MBR), code that informs the system about installed operating systems. To clarify, hard drives that use the MBR partitioning scheme have a tiny bit of data that is also called the “master boot record.” While your computer boots up, BIOS looks at the first sector of your hard drive for instructions. At this point, it doesn’t matter which OS you use or how many partitions you have. Without this bit of code, your OS will never load.

The master boot record also contains the partition table, which describes the number and size of partitions on the disk (see Figure 9.5). MBR partition tables support up to four partitions—the partition table is large enough to store entries for only four partitions. The instructions in the MBR use this table to determine which partition contains the active operating system.

• Figure 9.5 The master boot record

After the MBR locates the appropriate partition, the partition boot sector loads the OS on that partition. The partition boot sector stores information important to its partition, such as the location of the OS boot files (see Figure 9.6).

• Figure 9.6 Using the master boot record to boot an OS

MBR partition tables support two types of partitions: primary partitions and extended partitions. Primary partitions are designed to support bootable operating systems. Extended partitions are not bootable. A single MBR disk may have up to four primary partitions or up to three primary partitions and one extended partition.

Primary Partitions and Multiple Operating Systems

Primary partitions are usually assigned drive letters and appear in Windows Explorer/File Explorer (once you format them). The first lettered primary partition in Windows is always C:. After that, you can label the partitions D: through Z:.

Only primary partitions can boot operating systems. On an MBR disk, you can easily install four different operating systems, each on its own primary partition, and boot to your choice each time you fire up the computer.

Every primary partition on a single drive has a special setting stored in the partition table called active that determines the active partition. During boot-up, the BIOS/POST reads the MBR to find the active partition and boots the operating system on that partition. Only one partition can be active at a time because you can run only one OS at a time (see Figure 9.7).

• Figure 9.7 The active partition containing Windows

To control multiboot setups, many people use a free Linux-based boot manager called Grand Unified Bootloader (GRUB), shown in Figure 9.8. When the computer boots, the boot manager software yanks control from the MBR and asks which OS you want to boot. Once a partition is set as active, the partition boot sector loads the operating system.

• Figure 9.8 GRUB in action

Extended Partitions

With a four-partition limit, an MBR disk would be limited to only four drive letters if using only primary partitions. Extended partitions were invented to get around this limit. An extended partition may contain multiple logical drives, each of which can get a drive letter (see Figure 9.9).

• Figure 9.9 An extended partition containing multiple logical drives

Dynamic Disks

With the introduction of Windows 2000, Microsoft defined a type of partitioning called dynamic storage partitioning, better known as dynamic disks. Still in use today, Microsoft calls a drive structure created with a dynamic disk a volume. There is no dynamic disk equivalent to primary versus extended partitions. A dynamic disk volume is still technically a partition, but it can do things a regular partition cannot do.

First off, when you turn a hard drive into a dynamic disk, you can create as many volumes on it as you want. You’re not limited to four partitions.

Second, you can create—in software—new drive structures that you can’t do with MBR drives. Specifically, you can implement RAID, span volumes over multiple drives, and extend volumes on one or more drives. Table 9.1 shows you which volume types Windows 10/11 and Windows Server support.

Table 9.1 Dynamic Disk Compatibility

Simple volumes work a lot like primary partitions. If you have a hard drive and you want to make half of it E: and the other half F:, for example, you create two volumes on a dynamic disk. That’s it.

Spanned volumes use unallocated space on multiple drives to create a single volume. Spanned volumes are a bit risky: if any of the spanned drives fails, the entire volume is lost.

Striped volumes are RAID 0 volumes. You may take any two unallocated spaces on two separate hard drives and stripe them. But again, if either drive fails, you lose all of your data.

Mirrored volumes are RAID 1 volumes. You may take any two unallocated spaces on two separate hard drives and mirror them. If one of the two mirrored drives fails, the other keeps running.

RAID 5 volumes, as the name implies, are for RAID 5 arrays. A RAID 5 volume requires three or more dynamic disks with equal-sized unallocated spaces.

GUID Partition Table

MBR partitioning came out a long time ago, in an age where 32-MB hard drives were thought to be larger than you would ever need. While it’s lasted a long time as the partitioning standard for bootable drives, back around 2010 a new kid appeared in town with the power to outshine the aging partitioning scheme and assume all the functions of the older partition style.

The GUID partition table (GPT) partitioning scheme shares a lot with the MBR partitioning scheme, overcoming many of the MBR scheme’s limitations. Here are the big improvements:

On paper, a GPT drive looks a lot like an MBR drive, except it’s arranged by LBA instead of sectors (see Figure 9.10). LBA 0, for instance, is the protective MBR. This is a re-creation of the master boot record from MBR drives so that disk utilities know it is a GPT drive and don’t mistakenly overwrite any partition data.

• Figure 9.10 GUID partition table

Instead of the old master boot record and partition table, GPT drives use a GPT header and partition entry array. Both are located at the beginning and end of the drive so there is a protected backup copy. The partitions on a GPT drive go between the primary and backup headers and arrays, as shown in Figure 9.10.

You can configure Windows 10 and 11 to boot from GPT only if you use a UEFI motherboard. In other words, if you’re trying to install a current version of Windows on an ancient motherboard, you’re stuck with MBR. The same is true of macOS. Most Linux distributions can boot from GPT partitions with older BIOS or UEFI firmware.

Other Partition Types

The partition types supported by Windows are not the only partition types you may encounter; other types exist. One of the most common is called the hidden partition. A hidden partition is really just a primary partition that is hidden from your operating system. Only special BIOS tools may access a hidden partition. Hidden partitions are used by some PC makers to hide a backup copy of an installed OS that you can use to restore your system if you accidentally trash it—by, for example, learning about partitions and using a partitioning program incorrectly.

A swap partition is another special type of partition, but swap partitions are found only on Linux and UNIX systems. A swap partition’s only job is to act like RAM when your system needs more RAM than you have installed. Windows has a similar function with a page file that uses a special file instead of a partition, as you’ll recall from Chapter 4.

When to Partition

Partitioning is not a common task for an already-setup system. The two most common situations likely to require partitioning are when you install an OS on a new system and when you add an additional drive to an existing system. When you install a new OS, the installation program asks you how you would like to partition the drive. When you add a new hard drive to an existing system, every OS has a built-in tool to help you partition it.

Each version of Windows offers a different tool for partitioning hard drives. For more than 20 years, through the days of DOS and early Windows (up to Windows Me), we used a command-line program called FDISK to partition drives. Modern versions of Windows use a graphical partitioning program called Disk Management, shown in Figure 9.11. You’ll find it in the Quick Links menu or Computer Management in Administrative Tools. (Windows has an advanced command-line disk management tool as well, called diskpart, discussed in detail in Chapter 16.)

• Figure 9.11 Windows 10 Disk Management tool in Computer Management

Linux uses several tools for partitioning. The oldest is called fdisk—yes, the same name as the DOS/Windows tool (though case-sensitive). That’s where the similarities end, however, as Linux fdisk has a totally different command set. Even though every copy of Linux comes with the Linux fdisk, it’s rarely used because so many better partitioning tools are available. One of the GUI Linux partitioning tools is called GParted and is even conveniently provided by Ubuntu’s live CD.

In the early days of PCs, you couldn’t change a partition’s size or type (other than by erasing it) once you’d made it with any Microsoft tools. A few third-party tools, led by PartitionMagic, gave techs the tools to resize partitions without losing the data the partitions held. Current Microsoft Windows tools allow you to resize free space. Windows enables you to resize partitions nondestructively by shrinking or expanding existing partitions with available free space.

Partition Naming Problems

So far, you’ve learned that MBR and GPT disks use partitions and that dynamic disks use volumes. Unfortunately, when you create a new partition or volume in current versions of Windows (10 and 11), the tool (Disk Management) only shows that you’re about to create a volume. See Figure 9.12.

• Figure 9.12 Note that the context menu only mentions volumes, not partitions.

When working with older MBR disks, and even though the context menu says “New Simple Volume,” you create partitions on basic disks. Figure 9.13 shows Disk Management in Windows 11 with a basic disk with four partitions. The first three (from left to right) are primary partitions. The fourth and fifth structures on the right are a logical drive and some blank, unpartitioned “Free space” in an extended partition.

• Figure 9.13 Drive with four partitions displayed in Disk Management

■ Hard Drive Formatting

Once you’ve partitioned a hard drive, that partition is nothing more than a large number of blocks. Your operating system needs to store files, files with names like VacationMemories.mp4 or chrome.exe. We need to organize those blocks (see Figure 9.14).

• Figure 9.14 Big files require many blocks.

Formatting, the process of making a partition into something that stores files, does two things. First, it creates a file system—an organization of all the blocks contained in that partition, enabling file storage and retrieval. Second, formatting creates a root directory in the file system to enable the partition to store folders. You must format every partition/volume so they can hold and retrieve data.

Every operating system has its own file systems. For the Apple folks, macOS uses APFS. Linux users have lots to choose from; most use ext4, but you will see others with names like BTRFS, XFS, ZFS, and so on. Windows has file systems with names like NTFS, FAT32, and exFAT. Let’s first understand what a file system does (using Windows as an example), and then we will discuss the differences.

File Systems in Windows

Every version of Windows comes with a built-in formatting utility with which to create one or more file systems on a partition or volume. The versions of Windows in current use support three Microsoft file systems: FAT32, NTFS, and exFAT (for removable media). All Windows file systems organize blocks of data into groups called clusters. The size of each cluster varies according to the file system and the size of the partition. Windows uses clusters to overcome some of the limitations in addressing inherent to each file system. (I’ll add charts with each file system to show how the clusters scale.)

FAT32

The base storage area for hard drives is a block; each block stores up to 4096 bytes of data. In a small partition, each cluster is made up of one block. If a file is larger than 4096 bytes, it will use as many clusters as needed to store the file. The OS needs a method to fill one cluster, find another that’s unused, and fill it, continuing to fill clusters until the file is completely stored. Once the OS stores a file, it must remember which cluster holds the file, so it can be retrieved later. If an OS stores a file smaller than 4096 bytes, the rest of the cluster goes to waste. We accept this waste because most files are far larger than 4096 bytes.

MS-DOS version 2.1 first supported hard drives using a data structure and indexing system to keep track of stored data on the hard drive, and Microsoft called this structure the file allocation table (FAT). Think of the FAT as nothing more than a card catalog that keeps track of which clusters store the various parts of a file. The official jargon term for a FAT is data structure, but it is more like a two-column spreadsheet.

The left column (see Figure 9.15) gives each cluster a hexadecimal number from 00000000 to FFFFFFFF. Each hexadecimal character represents four binary numbers or 4 bits. Eight hex characters, therefore, represent 32 bits. If you do the math (2³²), you’ll find that there are over four billion clusters that can be tracked or indexed.

• Figure 9.15 32-bit FAT

We call this type of FAT a 32-bit FAT or FAT32. And it’s not just hard drives and SSDs that have FATs. Many USB flash drives use FAT32.

The right column of the FAT contains information on the status of clusters. All hard drives, even brand-new drives fresh from the factory, contain faulty blocks that cannot store data because of imperfections in the construction of the drives. The OS must locate these bad blocks, mark them as unusable, and then prevent any files from being written to them. This mapping of bad blocks is one of the functions of high-level formatting. After the format program creates the FAT, it marches through every block of the entire partition, writing and attempting to read from each block sequentially. If it finds a bad block, it places a special status code (0000FFF7) in the block’s FAT location, indicating that the cluster is unavailable for use. Formatting also marks the good blocks with code 00000000 (see Figure 9.16).

• Figure 9.16 Bad blocks marked

FAT32 in Action

Suppose you have a system with a drive using FAT32. When an application such as Microsoft Word tells the OS to save a file, Windows starts at the beginning of the FAT, looking for the first space marked “open for use” (00000000), and begins to write to that cluster. If the entire file fits within that one cluster, Windows places the code 0000FFFF (last cluster) into the cluster’s status area in the FAT. That’s called the end-of-file marker. Windows then goes to the folder storing the file and adds the filename and the cluster’s number to the folder list. If the file requires more than one cluster, Windows searches for the next open cluster and places the number of the next cluster in the status area, filling and adding clusters until the entire file is saved. The last cluster then receives the end-of-file marker (0000FFFF).

Let’s run through an example of this process, starting by selecting an arbitrary part of the FAT: from 03213ABB to 03213AC7. Assume you want to save a file called mom.txt. Before saving the file, the FAT looks like Figure 9.17.

• Figure 9.17 The initial FAT

Windows finds the first open cluster, 03213ABB, and fills it. But the entire mom.txt file won’t fit into that cluster. Needing more space, the OS goes through the FAT to find the next open cluster. It finds cluster 03213ABC. Before filling 03213ABC, the value 03213ABC is placed in 03213ABB’s status. Even after filling two clusters, more of the mom.txt file remains, so Windows must find one more cluster. The 03213ABD cluster has been marked 0000FFF7 (bad block), so Windows skips over 03213ABD, finding 03213ABE.

Before filling 03213ABE, Windows enters the value 03213ABE in 03213ABC’s status. Windows does not completely fill 03213ABE, signifying that the entire mom.txt file has been stored. Windows enters the value 0000FFFF in 03213ABE’s status, indicating the end of file (see Figure 9.18).

• Figure 9.18 End of file reached

After saving all of the clusters, Windows locates the file’s folder (yes, folders also are stored on blocks, but they get a different set of blocks, somewhere else on the disk) and records the filename, size, date/time, and starting cluster, like this:

If a program requests that file, the process is reversed. Windows locates the folder containing the file to determine the starting cluster and then pulls a piece of the file from each cluster until it sees the end-of-file cluster. Windows then hands the reassembled file to the requesting application.

Clearly, without the FAT, Windows cannot locate files. FAT32 automatically makes two copies of the FAT. One FAT backs up the other to provide special utilities a way to recover a FAT that gets corrupted—a painfully common occurrence.

Cluster Sizes in FAT32

Cluster sizes scale according to the file system. FAT32 offers 4-KB cluster sizes up to a partition size of 2 GB, which matches the size of a 4-KB block. Larger partitions require clusters with more blocks, thus reducing somewhat the efficiency of that drive. Table 9.2 shows the scaling effect in FAT32.

Table 9.2 FAT32 Cluster Sizes

FAT32 is still very much commonly used today, though not for operating system partitions. Rather, you’ll see it on smaller (< 32-GB) flash-media USB drives.

Fragmentation

Continuing with the example, let’s use Microsoft Word to save two more files: a letter called Important Document 31.docx and a letter named System Storage.docx. The Important Document 31.docx file takes the next three clusters—03213ABF, 03213AC0, and 03213AC1—and System Storage.docx takes two clusters—03213AC2 and 03213AC3 (see Figure 9.19).

• Figure 9.19 Three files saved

Assuming these files are all in the same folder, the file information looks like this:

Now suppose you erase mom.txt. Windows does not delete the block entries in the FAT for mom.txt when it erases the file. Windows only alters the information in the folder, simply changing the first letter of mom.txt to the lowercase Greek letter σ (sigma), as shown next. This causes the file to “disappear” as far as the OS knows. It won’t show up, for example, in Windows Explorer, even though the data still resides on the hard drive for the moment.

Note that under normal circumstances, Windows does not actually delete files when you press the DELETE key. Instead, Windows moves the file listing (but not the actual blocks) to a special hidden directory that you can access via the Recycle Bin. The files themselves are not actually deleted until you empty the Recycle Bin.

Because the data for mom.txt is intact, you could use some program to change the σ back into another letter and thus get the document back. A number of third-party undelete tools are available. Figure 9.20 shows one such program at work. Just remember that if you want to use an undelete tool, you must use it quickly. The space allocated to your deleted file may soon be overwritten by a new file.

• Figure 9.20 Piriform Recuva in action

Let’s say you just emptied your Recycle Bin. You now save one more file, Taxrec.xls, a big spreadsheet that will take six clusters, into the same folder that once held mom.txt. As Windows writes the file to the drive, it overwrites the space that mom.txt used, but it needs three more clusters. The next three available clusters are 03213AC4, 03213AC6 (skipping cluster 03213AC5, which is marked bad), and 03213AC7 (see Figure 9.21).

• Figure 9.21 The Taxrec.xls file, fragmented

Notice that Taxrec.xls is in two pieces, thus fragmented. Fragmentation takes place all of the time on FAT32 systems. Although the system easily negotiates a tiny fragmented file split into only two parts, excess fragmentation slows down the system during hard drive reads and writes. This example is fragmented into two pieces; in the real world, a file might fragment into hundreds of pieces, forcing the read/write heads to travel all over the hard drive to retrieve a single file. You can dramatically improve the speed at which the hard drive reads and writes files by eliminating this fragmentation.

Windows 10 and 11 come with an app called Optimize Drives (known in older versions of Windows as Disk Defragmenter) that can rearrange the files into neat contiguous chunks (see Figure 9.22). Windows does this automatically by default. Defragmentation is crucial for ensuring the top performance of a mechanical hard drive. The “Maintaining and Troubleshooting Hard Drives” section of this chapter gives the details on working with Optimize Drives in Windows.

• Figure 9.22 Windows 10 Optimize Drives

SSDs also have fragmentation of a sort, but the nature of an SSD means almost any page is as easily accessed as any other. In the first-generation SSDs, once data was written into a memory cell, it stayed there until the drive was full. Even if the cell contained file contents from a “deleted” file, the cell was not immediately erased or overwritten, because the SSD controller had no way to know the cell’s contents were deleted as far as the OS was concerned.

Because SSD memory cells have a finite number of times that they can be written to before wearing out, the first generation of SSDs waited until all the cells of an SSD were filled before erasing and reusing a previously written cell.

SSDs have a feature called trim that enables the OS to issue commands to clean up and reuse deleted areas. Windows runs trim automatically, so there’s rarely any reason at all to defragment any SSD—but we will develop this more when we discuss troubleshooting later in this chapter.

NTFS

The Windows format of choice these days is the New Technology File System (NTFS). NTFS came out a long time ago with the first version of Windows NT, thus the name. Over the years, NTFS has undergone several improvements. NTFS uses clusters of blocks and file allocation tables, but in a much more complex and powerful way compared to FAT32. NTFS offers six major improvements and refinements: redundancy, security, compression, encryption, disk quotas, and cluster sizing.

NTFS Structure

NTFS utilizes an enhanced file allocation table called the master file table (MFT). An NTFS partition keeps a backup copy of the most critical parts of the MFT in the middle of the disk, reducing the chance that a serious drive error can wipe out both the MFT and the MFT copy. Whenever you defragment an NTFS partition, you’ll see a small, immovable chunk somewhere on the drive, often near the front; that’s the MFT (see Figure 9.23).

• Figure 9.23 The NTFS MFT appears in a defragmenter program as the highlighted red blocks.

Security

NTFS views individual files and folders as objects and provides security for those objects through a feature called the access control list (ACL). Future chapters go into this in much more detail.

Compression

NTFS enables you to compress individual files and folders to save space on a hard drive. Compression makes access time to the data slower because the OS must uncompress files every time you use them, but in a space-limited environment, sometimes that’s what you have to do. Windows Explorer/File Explorer displays filenames for compressed files in blue.

Encryption

One of the big draws with NTFS is file encryption, making files unreadable to anybody who doesn’t have the right key. You can encrypt a single file, a folder, or a folder full of files. Microsoft calls the encryption utility in NTFS the encrypting file system (EFS), but it’s simply an aspect of NTFS, not a standalone file system. You’ll learn more about encryption when you read Chapter 13.

Disk Quotas

NTFS supports disk quotas, enabling administrators to set limits on drive space usage for users. To set quotas, you must log on as an Administrator, right-click the hard drive name, and select Properties. In the Drive Properties dialog box, select the Quota tab and make changes. Figure 9.24 shows configured quotas for a hard drive. Although rarely used on single-user systems, setting disk quotas on multiuser systems prevents any individual user from monopolizing your hard disk space.

• Figure 9.24 Hard drive quotas in Windows 10

Cluster Sizes

NTFS uses clusters, much like FAT32. The numbers equate to block size until you get to very large partitions. Table 9.3 shows the default cluster sizes for NTFS.

Table 9.3 NTFS Cluster Sizes

By default, NTFS supports partitions up to ~16 TB on a dynamic disk (though only up to 2 TB on a basic disk). By tweaking the cluster sizes, you can get NTFS to support partitions up to 16 exabytes, or 18,446,744,073,709,551,616 bytes! That might support any and all upcoming hard drive capacities for the next 100 years or so.

With so many file systems, how do you know which one to use? In the case of internal hard drives, you should use the most feature-rich system your OS supports. For all modern versions of Windows, use NTFS. External hard drives and flash drives still often use FAT32 because NTFS features such as the ACL and encryption can make access difficult when you move the drive between systems, but with that exception, NTFS is your best choice on a Windows-based system.

exFAT

Everyone loves USB flash drives. Their ease of use and convenience make them indispensable for those of us who enjoy sharing a program, some photos, or a playlist. But people today want to share more than just a few small files, and they can do so with larger flash drives. As flash drives grow bigger in capacity, however, the file system becomes a problem.

The file system we have used for years on flash drives, FAT32, does not work on drives larger than 2 TB. Worse, FAT32 limits file size to 4 GB. Because there is frequent need to physically transport many files that are often larger than 4 GB, Microsoft developed a replacement for FAT32.

The newer file system, called exFAT, breaks the 4-GB file-size barrier, supporting files up to 16 exabytes (EB) and a theoretical partition limit of 64 zettabytes (ZB). Microsoft recommends a partition size of up to 512 TB on today’s larger USB flash drives, which should be enough for a while. The exFAT file system extends FAT32 from 32-bit cluster entries to 64-bit cluster entries in the file table. Like FAT32, on the other hand, exFAT still lacks all of NTFS’s extra features such as permissions, compression, and encryption.

File Systems in macOS

From 1998 to 2017, MacOS used Hierarchical File System Plus (HFS+). Since 2017, however, all new Macs (and existing systems upgrading macOS) use the Apple File System (APFS) by default. Unlike HFS+, APFS is optimized for SSDs, allows for full disk encryption, and enables snapshots, among other improvements. Like Windows and Linux, macOS can read and write to several different file systems, such as FAT32 and exFAT, though only read NTFS.

File Systems in Linux

Most Linux distributions use a file system known as the Fourth Extended File System (ext4) by default. Some older distros use one of its predecessors, such as ext2 or ext3. The ext4 file system supports volumes up to 1 exabyte (EB) with file sizes up to 16 TB and is backward compatible with ext2 and ext3. In other words, you can mount an ext3 volume as an ext4 volume with no problems. You don’t need to know the details of ext3 or ext4, just that they are Linux file systems and that ext4 supports volumes up to 1 EB with file sizes up to 16 TB.

Many Linux distributions, especially at the enterprise level (big data centers), use the ZFS file system or its newer cousin, BTRFS (pronounced, “butter eff ess”). Both offer powerful copy and disk management features that go well beyond the scope of CompTIA A+. For more information on ZFS and most likely the file system wave of the future, even in Windows, start with the Wikipedia article about ZFS and follow the links to the sources.

■ The Partitioning, Formatting, and Pooling Process

Now that you understand the concepts of partitioning and formatting, let’s go through the process of setting up an installed hard drive by using different partitioning and formatting tools. At the end of the section, we’ll look at the process of creating a storage pool by creating a virtual disk. If you have access to a system, try following along with these descriptions. Don’t make any changes to a drive you want to keep, because both partitioning and formatting are destructive processes. The pooling process is also destructive. You cannot follow the procedure in that discussion unless you have a few drives to erase.

Bootable Media

Imagine you’ve built a brand-new PC. The hard drive has no OS, so you need to boot up something to set up that hard drive. Any software that can boot up a system is by definition an operating system. You need an optical disc or USB flash drive with a bootable OS installed. Any removable media that has a bootable OS is generically called a boot device or boot disc. Your system boots off of the boot device, which then loads some kind of OS that enables you to partition, format, and install an OS on your new hard drive. Boot devices come from many sources. All Windows OS installation media are boot devices (see Figure 9.25), as are Linux installation media.

• Figure 9.25 Windows 10 bootable media

Boot devices may also be a medium that has an image of an installation disc. These images are usually stored as a file with a name that has an extension of “.iso.” Image files may be on a traditional boot device, such as a disc or flash drive, but they can come from anyplace, such as on a network drive.

Every boot device has partitioning tools and a way to format a new partition. A hard drive must have a partition and has to be formatted to support an OS installation.

Partitioning and Formatting with the Installation Media

When you boot up Windows installation media and the installation program detects a hard drive that is not yet partitioned, it prompts you through a sequence of steps to partition and format the hard drive. Chapter 11 covers the entire installation process, but we’ll jump ahead and dive into the partitioning part of the installation here to see how this is done.

The process of partitioning and formatting when installing Windows is straightforward. You’ll go through a couple of installation screens (see Figure 9.26) where you select things such as language and get prompted for a product key and acceptance of the license agreement. Eventually you’ll get to the Where do you want to install Windows? dialog box (see Figure 9.27).

• Figure 9.26 Starting the Windows installation

• Figure 9.27 Where do you want to install Windows?

Click Next to do the most common partitioning and formatting action: creating a single C: partition, making it active, and formatting it as NTFS. Note that Windows creates three partitions: an EFI or System Reserved partition, the C: partition, and a Recovery partition. This is normal, the way the system was designed to work. Figure 9.28 shows a typical Windows installation in Disk Management.

• Figure 9.28 Disk Management showing Windows 11’s default partitions

If you want to do any custom partitioning or delete existing partitions, select one of the options. To create a new partition, click the New button. Type in an amount in megabytes that you want to use for a new partition, then click Apply. You will get a notice that Windows might create additional partitions for system files. When you click OK, Windows will create the 100-MB EFI or System Reserved partition as well as the partition you specified (see Figure 9.29). On GPT drives, it will create a 16-MB Reserved MSR partition that, according to Microsoft, helps with partition management. Any leftover drive space will be listed as Unallocated Space.

• Figure 9.29 New partition with System Reserved partition and Unallocated Space

Once you create a new partition, click the Format button. The installer won’t ask you what file system to use. Newer Windows versions can read FAT32 drives, but they won’t install to such a partition by default.

The example here has a 1-TB drive with a 58-GB partition and 965 GB of unallocated space. If you’ve gone through this process and have changed your mind, now wanting to make the partition use the full terabyte, what do you have to do? You can simply click the Extend button and then apply the rest of the unallocated space to the currently formatted partition. The Extend function enables you to tack unpartitioned space onto an already partitioned drive with the click of the mouse.

Disk Management

By now, you are familiar with Disk Management, because you’ve seen it in many previous figures. Since it is the primary graphical tool for partitioning and formatting drives after installation, I want to go into more depth on some of its features. The Run Command for Disk Management, dskmgmt.msc, allows you to do just about everything you need to do to a hard drive or solid-state drive in one handy tool, including initialization, creating volumes, changing drive letters, using dynamic disks, extending drives, and more. You can find Disk Management in the Quick Links menu, under Administrative Tools, or you can just type disk management in the Start menu and open it directly (see Figure 9.30).

• Figure 9.30 Opening Disk Management directly (shown as Create and format hard disk partitions)

Disk Initialization

Every hard drive in a Windows system has special information placed onto the drive through a process called disk initialization. (CompTIA refers to this as initializing a disk.) This initialization information includes identifiers that say “this drive belongs in this system” and other information that defines what this hard drive does in the system. If the hard drive is part of a software RAID array, for example, its RAID information is stored in the initialization. If it’s part of a spanned volume, this is also stored there.

All new drives must be initialized before you can use them. When you install an extra hard drive into a Windows system and start Disk Management, it notices the new drive and starts the Hard Drive Initialization Wizard. If you don’t let the wizard run, the drive will be listed as unknown (see Figure 9.31).

• Figure 9.31 Unknown drive in Disk Management

To initialize a disk, right-click the disk icon and select Initialize. You will get the option to select MBR or GPT as a partition style (see Figure 9.32). Once a disk is initialized, you can see the status of the drive—a handy tool for troubleshooting.

• Figure 9.32 Initializing a drive

Disk Management enables you to view the drive status of every mass storage device in your system. Hopefully, you’ll mostly see each drive listed as Healthy, meaning that nothing is happening to it and things are going along swimmingly. You’re also already familiar with the Unallocated and Active statuses, but here are a few more to be familiar with for the CompTIA A+ exams and real life as a tech:

A newly installed drive is always set as a basic disk. There’s nothing wrong with using basic disks, other than that you miss out on some handy features.

Creating Partitions and Volumes in Disk Management

To create partitions or volumes, right-click the unallocated part of the drive and select New Simple Volume. Disk Management runs the New Simple Volume Wizard. You’ll go straight to the sizing screen (see Figure 9.33).

• Figure 9.33 Specifying the simple volume size in the New Simple Volume Wizard

Specify a volume size and click Next. The wizard will ask if you want to assign a drive letter to the volume, mount it as a folder to an existing volume, or do neither (see Figure 9.34). In almost all cases, you’ll want to give simple volumes a drive letter.

• Figure 9.34 Assigning a drive letter to a volume

The last screen of the New Simple Volume Wizard asks for the type of format you want to use for this partition (see Figure 9.35). If your partition is 32 GB or less, you can make the drive FAT32 or NTFS. Windows requires NTFS on any partition greater than 32 GB. Although FAT32 supports partitions up to 2 TB, Microsoft wants you to use NTFS on larger partitions and creates this limit. With today’s multi-terabyte drives, there’s no good reason to use anything other than NTFS in Windows. In addition to the file system selection, you are offered a checkbox to perform a quick format or a full format. A quick format does not test the blocks as part of the format process, while the full format option does. (See “Formatting a Partition” later in this chapter for more details.)

• Figure 9.35 Choosing a file system type

You have a few more tasks to complete at this screen. You can add a volume label if you want. You can also choose the size of your clusters (Allocation unit size). You can sure speed up the format if you select the Perform a quick format checkbox. This will format your drive without checking every block. It’s fast and a bit risky, but new hard drives almost always come from the factory in perfect shape—so you must decide whether to use it or not.

Last, if you chose NTFS, you may enable file and folder compression. If you select this option, you’ll be able to right-click on any file or folder on this partition and compress it. To compress a file or folder, choose the one you want to compress, right-click, and select Properties. Then click the Advanced button and turn compression on (see Figure 9.36). Compression is handy for opening up space on a hard drive that’s filling up.

• Figure 9.36 Turning on compression

Dynamic Disks

You create dynamic disks from basic disks in Disk Management. Once you convert a drive from a basic disk to a dynamic disk, primary and extended partitions no longer exist; dynamic disks are divided into volumes instead of partitions. Because current versions of Windows call partitions volumes, the change to dynamic disk isn’t obvious at all.

To convert a basic disk to dynamic, just right-click the drive icon and select Convert to Dynamic Disk (see Figure 9.37). The process is very quick and safe, although the reverse is not true. The conversion from dynamic disk to basic disk first requires you to delete all volumes off the hard drive.

• Figure 9.37 Converting to a dynamic disk

Once you’ve converted the disk, you can make one of the five types of volumes on a dynamic disk: simple, spanned, striped, mirrored, or RAID 5. You’ll next learn how to implement the three most common volume types. The final step involves assigning a drive letter or mounting the volume as a folder.

Simple Volumes A simple volume acts just like a primary partition. If you have only one dynamic disk in a system, it can have only a simple volume. It’s important to note here that a simple volume may act like a traditional primary partition, but it is very different because you cannot install an operating system on it.

In Disk Management, right-click on any unallocated space on the dynamic disk and choose New Simple Volume to run the New Simple Volume Wizard (see Figure 9.38). You’ll see a series of screens that prompt you on size and file system, and then you’re finished. Figure 9.39 shows Disk Management with three simple volumes.

• Figure 9.38 Starting the New Simple Volume Wizard

• Figure 9.39 Simple volumes

Spanning Volumes You can extend the size of a simple volume to any unallocated space on a dynamic disk. You can also extend the volume to grab extra space on completely different dynamic disks, creating a spanned volume. This capability is very helpful if you manage an older system that needs a little more space but you don’t have time or inclination to upgrade. To extend or span, simply right-click the volume you want to make bigger, and choose Extend Volume from the options (see Figure 9.40). This opens the Extend Volume Wizard, which prompts you for the location of free space on a dynamic disk and the increased volume size you want to assign (see Figure 9.41). If you have multiple drives, you can span the volume just as easily to one of those drives.

• Figure 9.40 Selecting the Extend Volume option

• Figure 9.41 The Extend Volume Wizard

The capability to extend and span volumes makes dynamic disks worth their weight in gold. If you start running out of space on a volume, you can simply add another physical hard drive to the system and span the volume to the new drive. This keeps your drive letters consistent and unchanging so your programs don’t get confused, yet enables you to expand drive space when needed.

You can extend or span any simple volume on a dynamic disk, not just the “one on the end” in the Disk Management console. You simply select the volume to expand and the total volume increase you want. Figure 9.42 shows a simple 97.66-GB volume named Extended that has been enlarged an extra 453.39 GB in a portion of the hard drive, skipping the 48.83-GB volume in the middle of the drive. This created a 551.05-GB volume. Windows has no problem skipping areas on a dynamic disk.

• Figure 9.42 Extended volume

Striped Volumes If you have two or more dynamic disks in a PC, Disk Management enables you to combine them into a striped volume. Although Disk Management doesn’t use the term, you know this as a RAID 0 array. A striped volume spreads out blocks of each file across multiple disks. Using two or more drives in a group called a stripe set, striping writes data first to a certain number of clusters on one drive, then to a certain number of clusters on the next drive, and so on. It speeds up data throughput because the system has to wait a much shorter time for a drive to read or write data. The drawback of striping is that if any single drive in the stripe set fails, all the data in the stripe set is lost.

To create a striped volume, right-click on any unused space on a drive, choose New Volume, and then choose Striped. The wizard asks for the other drives you want to add to the stripe, and you need to select two unallocated spaces on other dynamic disks. Select the other unallocated spaces and go through the remaining screens on sizing and formatting until you’ve created a new striped volume (see Figure 9.43). The two stripes in Figure 9.43 appear to have different sizes, but if you look closely you’ll see they are both 300 GB. All stripes must be the same size on each drive.

• Figure 9.43 Two striped drives

Mirrored Volumes Windows 10 and 11 can create a mirror set with two drives for data redundancy. You know mirrors from Chapter 8 as RAID 1. To create a mirror, right-click on unallocated space on a drive and select New Mirrored Volume (see Figure 9.44). This runs the New Mirrored Volume Wizard. Click Next to continue. Select an available disk in the Available box and click the Add button to move it to the Selected box (see Figure 9.45). Click Next to get to the by-now-familiar Assign Drive Letter or Path dialog box and select what is appropriate for the PC.

• Figure 9.44 Selecting a new mirror

• Figure 9.45 Selecting drives for the array

Other Levels of RAID Disk Management enables you to create a RAID 5 array that uses three or more disks to create a robust solution for storage. This applies to all the Professional editions of Windows. Unfortunately for users of those operating systems, you can only make the array on a Windows Server machine that you access remotely across a network. (Starting with the Professional and Enterprise editions of Windows 8, Microsoft includes Storage Spaces, an alternative way to do software pseudo-RAID in the form of pooling; one option closely resembles RAID 5. See the “Storage Spaces” section later in the chapter for more details.)

Disk Management cannot do any nested RAID arrays. So if you want RAID 0+1 or RAID 1+0 (RAID 10), you need to use hardware RAID.

Mounting Partitions as Folders

While partitions and volumes, other than the one Windows boots from, can be assigned a drive letter, D: through Z:, they can also be mounted as a folder on another drive, also known as a mount point. This enables you to use your existing folders to store more data than can fit on a single drive or partition/volume (see Figure 9.46).

• Figure 9.46 Mounting a drive as a folder

Imagine you use your Documents folder on a Windows machine to store your digital photos. As your collection grows, you realize your current 500-GB SSD is running out of space. You’re willing to buy another drive, but you have a great organizational structure in your existing Documents folder and you don’t want to lose that. You don’t have to move everything to the new hard drive, either.

After you install the new hard drive, you can mount the primary partition (or logical drive) as a folder within the existing Documents folder on your C: drive (for example, C:UsersMikeDocumentsMy Photos). At this point the drive doesn’t have a letter (though you could add one later, if you wanted). To use the new drive, just drop your files into the My Photos folder. They’ll be stored on the second drive, not the original 500-GB drive (see Figure 9.47). Amazing!

• Figure 9.47 Adding photos to the mounted folder stores them on the second hard drive.

To create a mount point, right-click on an unallocated section of a drive and choose New Simple Volume. This opens the appropriately named wizard. In the second screen, you can select a mount point rather than a drive letter (see Figure 9.48). Browse to a blank folder on an NTFS-formatted drive or create a new folder and you’re in business.

• Figure 9.48 Choosing to create a mounted volume

Assigning/Changing Drive Letters and Paths

Disk Management enables you to modify the drive letter, path, or mount point on currently installed mass storage devices. Right-click a drive and select Change Drive Letter and Paths. You can assign a desired drive letter to an optical drive—say, from D: to Z:, for example. Or, you can change a hard drive from D: to a non-letter-named mount point so it shows up in Windows Explorer/File Explorer as a subfolder. You have a ton of flexibility with Disk Management.

Formatting a Partition

You can format any Windows partition/volume in Windows Explorer/File Explorer. Just right-click on the drive name and choose Format. You’ll see a dialog box that asks for the type of file system you want to use, the cluster size, and a volume label (see Figure 9.49). You can also do a quick format or compress the volume. The Quick Format option tells Windows not to test the blocks and is a handy option when you’re in a hurry—and feeling lucky.

• Figure 9.49 Format New Volume dialog box

Disk Management is today’s preferred formatting tool for Windows. When you create a new partition or volume, the wizard also asks you what type of format you want to use. Always use NTFS unless you’re that rare and strange person who wants to dual-boot some ancient version of Windows.

All OS installation media partition and format as part of the OS installation. Windows simply prompts you to partition and then format the drive. Read the screens and you’ll do great.

Storage Spaces

With Windows 10 and 11, you can group one or more physical drives of any size into a single storage pool. These drives can be internal HDD or SSD or external storage connected via USB. It’s pretty sweet. Storage Spaces functions like a RAID management tool, except it goes well beyond the typical tool. Here’s the scoop.

First off, to run the tool, get to the Start screen and type storage spaces. Storage Spaces will show up in the Search. Click on it to run the program. The opening screen gives you pretty much a single option, to Create a new pool and storage space (see Figure 9.50). Click that option.

• Figure 9.50 Storage Spaces waiting to create the first pool

Storage Spaces will show you the available installed physical drives (see Figure 9.51). Select the drives you want to include in the pool and click the Create pool button.

• Figure 9.51 Drives available to use in a storage pool

Once you’ve created a pool, you need to select what Microsoft calls the resiliency mechanism, which essentially means providing one or more layers of redundancy so you can lose a hard drive or two and not lose any data. Sounds a lot like RAID, doesn’t it? Figure 9.52 shows the Create a storage space window with a Two-way mirror storage layout. Here’s where Storage Spaces gets pretty much cooler than any RAID management tool.

• Figure 9.52 Ready to create the storage space

Storage Spaces offers three different types of storage spaces:

When a disk fails in a space, Storage Spaces sends a warning through the standard Windows Action Center messaging. You can open Storage Spaces to reveal the failed drive and replace the drive readily.

Storage Spaces enables you to do one more very cool action: future-proof your storage needs. The thin provisioning feature means you can create a space with more capacity than your current physical drives provide. You might have a storage pool composed of two 2-TB drives and one 3-TB drive, laid out as a two-way mirror. Rather than limit your new space to a 3-TB capacity, you can assign whatever capacity you want, such as 12 TB, because you know your movie collection will grow. When you start to reach the capacity of the physical drives in the pool, Storage Spaces will tell you and enable you to add more physical capacity at that time. Thin provisioning means you don’t have to redo an array or space when you reach the limits of current hardware.

■ Maintaining and Troubleshooting Hard Drives

Hard drives are complex mechanical and electrical devices. With platters spinning at thousands of rotations per minute, they also generate heat and vibration. All of these factors make hard drives susceptible to failure. In this section, you will learn some basic maintenance tasks that will keep your hard drives healthy, and for those inevitable instances when a hard drive fails, you will also learn what you can do to repair them.

Pay attention to the terminology used both on the CompTIA A+ exam and in the field. Current storage for drives focuses on blocks and logical block addressing. A block is one step above the physical layout of the drive, which gives a lot of flexibility in the media. Microsoft continues to use the term cluster to refer to locations in their file allocation tables. With NTFS, a cluster and a block are pretty much the same thing, a 4-KB chunk of a drive (until you get partitions larger than 16 TB). The official term for a cluster is an allocation unit. You’ll see all three terms used interchangeably in the field.

Maintenance

Hard drive maintenance can be broken down into two distinct functions: checking the disk occasionally for failed blocks, and keeping data organized on the drive so it can be accessed quickly.

Error Checking

Individual blocks on hard drives sometimes go bad. There’s nothing you can do to prevent this from happening, so it’s important that you check occasionally for bad blocks on drives. The tools used to perform this checking are generically called error-checking utilities, although the term for an older Microsoft tool—chkdsk (pronounced “checkdisk”)—is often used. Chkdsk is a command-line utility. Microsoft has a graphical version of this tool, which is called Error checking in Windows 10 and 11. macOS uses the Disk Utility. Linux offers a command-line tool called fsck. Whatever the name of the utility, each does the same job: when the tool finds bad blocks, it puts the electronic equivalent of orange cones (placing 0000FFF7 in the FAT/MFT) around them so the system won’t try to place data in those bad blocks.

Most error-checking tools do far more than just check for bad blocks. They go through all the drive’s filenames, looking for invalid names and attempting to fix them. They look for blocks that have no filenames associated with them (we call these lost chains) and erase them or save them as files for your review. From time to time, the underlying links between parent and child folders are lost, so a good error-checking tool checks every parent and child folder. With a folder such as C:TestData, for example, the tool makes sure that the Data folder is properly associated with its parent folder, C:Test, and that C:Test is properly associated with its child folder, C:TestData.

To access Error checking on a Windows system, open Windows Explorer/File Explorer, right-click on the drive you want to check, and choose Properties to open the drive’s Properties dialog box (see Figure 9.53). Select the Tools tab and click the Check or Check now button.

• Figure 9.53 The Tools tab in the Properties dialog box

In macOS, you’ll find Disk Utility in the Utilities folder. When open, you’ll get one option to try and fix any problems with your disk, First Aid (see Figure 9.54). First Aid checks for errors and will attempt to repair them if it can. You can run First Aid on a disk while macOS is booted, but sometimes Disk Utility won’t be able to work its magic on your disk because it’s in use and can’t be unmounted. If this happens, you need to reboot the system and press COMMAND-R until the Recovery partition loads. You can then load Disk Utility from here and run First Aid on the ailing disk again.

• Figure 9.54 Disk Utility options

Defragmentation

You read about fragmentation earlier in this chapter. Fragmentation of blocks increases your hard disk drive access times dramatically. It’s a good idea to defragment—or defrag—your traditional spinning drives as part of monthly maintenance. You access the defrag tool Optimize Drives the same way you access Error checking—right-click a drive in Windows Explorer/File Explorer and choose Properties—except you click the Optimize or Defragment now button on the Tools tab to open Optimize Drives.

Defragmentation is not interesting to watch but Windows today makes it a non-event by automatically defragging HDDs once a week by default (see Figure 9.55). While this takes care of dealing with spinning hard drives, what about the SSDs that most of our systems use today? In that case, Windows still needs to optimize the drive, but it will perform a retrim, which is jargon for letting the SSD know what sectors are not being used by the file system. This lets the SSD controller erase them so they can be used again in the future. Like the classic defragmentation on an HDD we discussed earlier, this is important for keeping your SSD performance at its peak.

• Figure 9.55 Optimize Drives, showing its default weekly schedule

Disk Cleanup

Did you know that the average hard drive is full of trash? Not the junk you intentionally put in your hard drive such as the terabytes of video of your cat Sparkles sitting in every box she can fit into. This kind of trash is all the files that you never see that Windows keeps for you. Here are a few examples:

Every hard drive eventually becomes filled with lots of unnecessary trash. All versions of Windows tend to act erratically when the drives run out of unused space. Fortunately, all versions of Windows have a powerful tool called Disk Cleanup (see Figure 9.57). You can access Disk Cleanup in Windows by clicking the Start button and typing disk cleanup. Click its icon to run the program.

• Figure 9.57 Disk Cleanup

Disk Cleanup gets rid of the four types of files just described (and a number of others). Run Disk Cleanup once a month or so to keep plenty of space available on your hard drive.

1101

Troubleshooting Hard Drive Implementation

There’s no scarier computer problem than an error that points to trouble with a hard drive. This section looks at some of the more common problems that occur with hard drives and how to fix them. These issues fall into four broad categories: installation errors, data corruption, dying hard drives, and RAID issues.

Installation Errors

Installing a drive and getting to the point where it can hold data requires four distinct steps: connectivity, system setup, partitioning, and formatting. If you make a mistake at any point on any of these steps, the drive won’t work. The beauty of this is that if you make an error, you can walk back through each step and check for problems. The “Troubleshooting Hard Drive Installation” section in Chapter 8 covered physical connections and CMOS system setup, so this section concentrates on the latter two issues.

Partitioning Partitioning errors generally fall into two groups: failing to partition at all, and making the wrong size or type of partition. You’ll recognize the former type of error the first time you open Windows Explorer/File Explorer after installing a drive. If you forgot to partition it, the drive won’t even show up in Windows Explorer/File Explorer, only in Disk Management. If you made the partition too small, that’ll become painfully obvious when you start filling it up with files.

The fix for partitioning errors is simply to open Disk Management and do the partitioning correctly. Just right-click and select Extend Volume to correct the mistake. Remember that deleting any volume will permanently delete any data on that drive.

Formatting Failing to format a drive makes the drive unable to hold data. Accessing the drive in Windows results in a drive “is not accessible” error, and from a C:> prompt, you’ll get an “Invalid media type” error. Format the drive unless you’re certain that the drive has a format already. Corrupted files can create the invalid media error. Check the upcoming “Data Corruption” section for the fix.

Most of the time, formatting is a slow, boring process. But sometimes the drive makes “bad sounds” and you start seeing errors like the one shown in Figure 9.58 at the top of the screen. Remember, an allocation unit is another term for a block or cluster.

• Figure 9.58 The “Trying to recover lost allocation unit” error

The drive has run across a bad cluster and is trying to fix it. For years, I’ve told techs that seeing this error a few times doesn’t mean anything; every drive comes with a few bad spots. This is no longer true. Modern drives hide a significant number of extra blocks that they use to replace bad blocks automatically. If a new drive gets a lot of “Trying to recover lost allocation unit” errors, you can bet that the drive is dying and needs to be replaced. Get the hard drive maker’s diagnostic tool to be sure. Bad clusters are reported by S.M.A.R.T. (introduced in Chapter 8), one of several S.M.A.R.T. errors possible.

Mental Reinstallation Focus on the fact that all of these errors share a common thread—you just installed a drive! Installation errors don’t show up on a system that has been running correctly for three weeks; they show up the moment you try to do something with the drive you just installed. If a newly installed drive fails to work, do a “mental reinstallation.” Does the drive show up in the UEFI or traditional BIOS setup screens? No? Then recheck the data and power cables. If it does show up, did you remember to partition and format the drive? Did it need to be set to active? These are commonsense questions that come to mind as you march through your mental reinstallation. Even if you’ve installed thousands of drives over the years, you’ll be amazed at how often you do things such as forget to plug in power to a drive. Do the mental reinstallation—it really works!

Data Corruption

All hard drives occasionally get corrupted data in individual blocks. Power surges, accidental shutdowns, corrupted installation media, and viruses, along with hundreds of other problems, can cause this data loss/corruption. In most cases, this type of error shows up while Windows is running. Figure 9.59 shows a classic example.

• Figure 9.59 A corrupted data error

You may also see Windows error messages saying one of the following:

If core boot files become corrupted, you may see text errors at boot, such as the following:

The first fix for any of these problems is to run the Error checking utility. Error checking will go through and mark bad blocks and, hopefully, move your data to a good block. If the same errors continue to appear after you run the Error checking utility, there’s a chance that the drive has too many bad blocks and may need to be recycled.

Almost all drives today take advantage of built-in error correction code (ECC) that constantly checks the drive for bad blocks. If the ECC detects a bad block, it marks the block as bad in the drive’s internal error map. Don’t confuse this error map with a FAT. The partitioning program creates the FAT. The drive’s internal error map was created at the factory on reserved drive heads and is invisible to the system. If the ECC finds a bad block, you will get a corrupted data error as the computer attempts to read the bad block. Disk-checking utilities fix this problem most of the time.

Dying Hard Drive

Physical problems are rare, thankfully, but they are devastating when they happen. If a hard drive is truly damaged physically, there is nothing that you or any service technician can do to fix it. Fortunately, hard drives are designed to take a phenomenal amount of punishment without failing. Physical problems manifest themselves in several ways. One common problem you start getting are extended read/write times, which is caused by a connection to a file being interrupted or terminated and could result in data corruption. Other signs that the hard drive might be dying is that the drive works properly but makes a lot of noise, or the drive seems to disappear. You might get a failure to boot after experiencing any of these events.

Windows will give you error messages with read/write failures. Good hard drives don’t fail to read or write. Only dying ones have these problems.

All mechanical hard drives make noise—the hum as the platters spin and the occasional slight scratching noise as the read/write heads access sectors are normal. However, if your drive begins to make any of the following sounds, it is about to die:

Another way you can tell if your hard drive is having issues is by looking at the computer’s light-emitting diode (LED), which is located on the front of the computer case. There are LEDs that provide information on the health of the computer. The activity LED (green) and the status LED (bicolor, green/amber) can help you diagnose a hard drive problem such as if a drive has failed (or if there is a predicted failure reported by the drive), the slot is empty, the drive is rebuilding, etc.

If all else fails, back up your critical data and replace the drive. Windows comes with a decent backup utility, but don’t be afraid to research third-party options if it doesn’t meet your needs. The cloud backup services are particularly nice options because they provide off-site protection in addition to backing up your data.

You’ll know when a drive simply dies. If it’s the drive that contains your operating system, the system will lock up. When you try to restart the computer, you’ll see this error message or something similar to it:

Bootable Device Not Found

If it’s a second drive, it will simply stop showing up in Windows Explorer/File Explorer. The first thing to do in either case is to access the system setup program and see if autodetect sees the drive. If it does, you do not have a physical problem with the drive. If autodetect fails, shut off the system and remove the data cable, but leave the power cable attached. Restart the system and listen to the drive. If the drive spins up, you know it is getting good power. This is usually a clue that the drive is probably good. In that case, you need to look for more mundane problems such as an unplugged data cord or jumpers incorrectly set (PATA only). If the drive doesn’t spin up, try another power connector. If it still doesn’t spin up and you’ve triple-checked the jumpers and data cable, you have a problem with the onboard electronics and the drive is dead.

If the drive is an SSD, the troubleshooting process is similar: either the power or motherboard controller is bad, a power or data cable has failed, or the drive electronics are dead. Start with the power cable, changing it for a known-good one. Then try a known-good data cable using the original motherboard connection. Next, try a different motherboard connector. Still haven’t got it? It’s likely a bad drive, but you should confirm so by testing it in another known-good computer to see if it is detected by UEFI/BIOS and then by Windows Disk Management.

Troubleshooting RAID

For the most part, drive problems in a RAID array are identical to those seen on individual drives. There are a couple of errors unique to RAID, however, that need their own separate discussion.

Drive Not Recognized If you’re using hardware RAID and the configuration firmware doesn’t recognize one of the drives, first check to make sure the drives are powered and that they are connected to the proper connections. This is especially true of motherboards with onboard RAID that require you to use only certain special RAID connectors.

RAID Stops Working When one of the drives in a RAID array fails, several things can happen depending on the type of array and the RAID controller. With RAID 0, the effect is dramatic. Many enthusiasts use RAID 0 for their OS drive to make it snappier. If you’re running such a rig that then loses a drive, you’ll most likely get a critical stop error that manifests as some sort of proprietary crash screen. Windows will show a Blue Screen of Death (BSoD), for example. On reboot, the computer will fail to boot or you’ll get a message such as Missing Drive in OS or Bootable device not found. You lose all your data because there’s no redundancy on a stripe set. You may see error messages before the crash related to read/write failures. On macOS machines, a failing drive or array may result in the Spinning Pinwheel of Death (SPoD). If there are no other systemic problems such as low RAM or low disk space, it’s time to break out RAID- or disk-diagnostic tools such as S.M.A.R.T. reader software.

All the other levels of RAID tend to do nothing extraordinary when one drive in the array fails. When you reboot the system, that’s when the RAID controller (if hardware) or Windows (if you’ve used the built-in tools) will squeal and tell you that a drive has failed.

Often, the failure of a drive will cause access to the contents of the drive to slow to a crawl, and that slow performance is your clue to check Device Manager or the RAID controller firmware. Some drive failures will cause the computer to crash. Others will show no effects until you get the error messages at reboot.

Regardless of the reason a RAID stops working or the effects, the fix is simple. Replace the failed drive and let the RAID rebuild itself. Life is good. If you need to know the reason for the failure, trying running S.M.A.R.T. reader software on the failed drive. If the drive electronics have some functionality, you may get results.

RAID Not Found The CompTIA A+ 220-1101 exam objectives use the term “RAID not found,” which doesn’t really exist as an error but instead implies a series of errors where an existing RAID array suddenly fails to appear. The problem with these errors is that they vary greatly depending on the make and model of hardware RAID or (heaven forbid) if you used software RAID.

A properly functioning hardware RAID array will always show up in the configuration utility. If an existing array stops working and you enter the configuration utility only to find the array is gone, you have big trouble. This points to either dead drives or faulty controllers. In either case they must be replaced.

If the array is gone but you can still see the drives, then the controller may have broken the array on its own. This is a rare action that some controllers take to try to save data. You should at least try to rebuild the array using whatever tools the controllers provide.