Disk Management

The Disk Management utility (see Figure 29.2) is responsible for the creation, deletion, alteration, and maintenance of storage volumes in a system. This tool is located within the Computer Management interface of Administrative Tools (accessed through Start, Control Panel, Administrative Tools, Computer Management, Disk Management). Another means is by right-clicking My Computer and choosing Manage. Using the Disk Management utility, you also can assign the drive letters used by your CD and hard disk drives.

Figure 29.2. The Disk Management tool as part of Computer Management.

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If the Administrative Tools menu selection is not displayed on the Start menu, right-click over the Start menu and select Properties, click Customize, click the Advanced tab, scroll down to the System Administrative Tools items, and then select the appropriate radio button.

If you enable the Control Panel to act as a menu, Administrative Tools can be accessed through it off the Start menu as well.

As discussed in Chapter 27, "System Utilities," this single interface lets you manage both local and remote computers using the various administration utilities shown in the left pane. Using this interface, I will show you how to perform different procedures on your existing and new hard disks. The process is quite simple for most of the operations because you will be presented with a wizard to complete them.

Most operations on disks can be performed by right-clicking the disk or volume you want to affect. As usual, you are presented with a context-sensitive menu from which you can perform any actions relating to the volume or disk you clicked. You can also see, from the graphical layout in the Disk Management, just what is going on with your disks at any given time. As always, you can select the Help option from within any menu to get an explanation of the operations available to you.

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You can change the way specific types of volumes are displayed in Disk Management. To do this, click the Settings button at the end of the button bar. From there, you can select the color you would like to use to represent any of the various disk states that will be shown by the Disk Management. By selecting the Scaling tab from the Settings dialog box, you can also change the way in which the Disk Management shows the scaling of each disk. This capability is particularly useful if you would like the scale display to be more representative of the actual physical sizes of your disks.

Assigning Drive Letters and Joining Volumes

Windows automatically assigns letters to the drives. However, this assignment might not suit your system; for example, you might have mapped a network drive to the same letter that Windows assigns to a new drive.

Using the Disk Management, you can easily assign logical drive letters to your hard disks and removable drives such as CD-ROMs. You can't change the drive letter of your boot drive (usually the C: drive), but you can change any of the others.

CAUTION

Note that many MS-DOS-based and Windows-based programs make references to a specific drive letter (for example, environment variables). If you modify the drive letter of a drive with these programs installed, they may not function correctly.

To change the letter, right-click the disk volume or drive in the bottom-right pane of the Disk Management, and select Change Drive Letter and Paths. A dialog box appears, listing the current drive letter assignment. Click Change. Under Assign a Drive Letter, choose the desired new letter. Click OK and confirm that you really do want to make the change.

In addition to or instead of assigning a drive letter to a disk drive or partition, you can "graft" the disk volume onto another. Windows lets you specify a folder that will become the mount point for the new drive. For example, I might create a folder named C:\TEMP. Because I want lots of space for it, I can install a new hard drive and, instead of assigning it a drive letter, tell Windows to access it through C:\TEMP. My C:\TEMP files and subfolders are then stored on the alternate drive.

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By using a mount point, you can add space to the folders under the mount point folder using an available drive. This is a good way to add space in a controlled fashion for a specific purpose, such as storing scratch files or Web page images.

Grafting Versus Dynamic Disks

Assigning mount points is different from what happens when you aggregate dynamic disks into one large volume. Although dynamic disks and regular disks (simple disks) both support the use of mount points, dynamic disks can create one large, apparently contiguous disk space. Mount points graft subsequently added drives at a folder, sort of like grafting two trees by tying together a branch from each tree. Figures 29.3 and 29.4 illustrate the differences between the two approaches. In Figure 29.4, I've grated my music files from drive G:\MUSIC into the mount point on drive H:\MP3.

Figure 29.3. You can join drives two different ways. Using mount points is one way, and using dynamic disk aggregation is another.

Figure 29.4. Assigning a partition or volume to a folder rather than a drive letter joins the volume to an existing volume. The contents of the added volume appear as subdirectories of the mount point folder.

NOTE

You can graft new volumes or disks onto a folder only on an NTFS-formatted drive. The new volume can have any format, however.

NOTE

If the folder you specify as the mount point already contains files, they are inaccessible as long as the drive-to-path mapping exists because that folder is now remapped into the new location. The original files reappear if you delete the drive path. Therefore, it's usually a good idea to create a new folder as a mount point or delete all of the contents of an existing folder before establishing the mount point.

Even if you have several hard drives and CD-ROM drives, you can graft them all together onto your C: drive, making it look like one big file system. It's a great management concept: You can add space to your file system by attaching new disk volumes right into the original folder structure. (Unix users are probably smirking at this point because the Unix operating system has worked this way since it was written in the 1970s.)

If you mount a drive and assign it a drive letter, you can gain access to it through both pathways.

To graft a disk volume to an existing file system, follow these steps:

1.	Create the folder that is to serve as the mount point for the new drive or volume.
2.	Highlight the new drive or volume in Disk Management.
3.	Right-click, select Change Drive Letter and Paths, and click Add.
4.	Select Mount in the Following Empty NTFS Folder.
5.	Enter the folder's pathname, or click Browse to locate it.
6.	Click OK to save the path.

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When Explorer shows you free disk space on the original drive, it measures only the space on the physical drive, not space on any grafted drives. You'll actually have more space than you think because files on the grafted folders are stored on another volume. If you want, you can also assign a drive letter to the added volume so that you can view and monitor its free space directly.

Alternatively, you can use the command prompt, change to the folder in the grafted volume, and use the DIR command. The DIR command lists free space on the actual current volume.

You can assign a given drive or volume to at most one drive letter, but an arbitrary number of paths. (It's a little bit strange to see the same files appear in several different places, so I recommend that you not go nuts with this feature.)

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If you're running out of room on your C: drive, see whether it makes sense in your situation to add lots of space to just one folder (for example, My Documents). If it does, install and format a new hard drive, and assign it a letter. Copy the original folder to the new drive. Then add a path to the new hard drive using the name of the original folder. This way, you can preserve your original data and have lots of room for growth.

By the way, this "grafting" technique works with both basic and dynamic NTFS disks. Only Windows dynamic disks can be "grown" by changing their partition size on-the-fly. If you use a basic-formatted disk, as most users do, the grafting trick is a good one to know.

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Another really good time to use this feature is when you've backed up application data onto a CD-R or CD-RW. If you want to use the backed-up data in an emergency, you can add a path for your CD-ROM drive to make its files appear in the original data location expected by your application. That way, you can use the data off the CD-R without restoring it to disk or reconfiguring your application. Later, you can delete the path to regain access to the "real" folder.

Dynamic Disk Management

If you are using only Windows XP on a system, upgrading your storage devices to dynamic disks is usually the best way to go because of the many advantages of the new dynamic disk storage system. Remember, though, that you can't boot into or read your dynamic disks from any other operating system after you upgrade them. You can upgrade a disk through Disk Management, right-clicking the drive's icon in the bottom pane (click the part of the graphical display that reads "Disk 0," "Disk 1," and so on, not on the volume), and choosing Upgrade to Dynamic Disk. Then choose the disk and click OK. Next, just follow the wizard, and you'll be set.

CAUTION

Don't upgrade to dynamic disks until you read all the material here on the topic and review the Help system's coverage of it in Disk Management. As you learned earlier in this chapter, dynamic disks cannot be changed back to basic disks without completely destroying any partitions and reformatting the disk. If you have to do that, right-click the volume and select Delete Volume. From there, you can just re-create your simple volume by right-clicking a disk and going through the applicable wizard. Also, remember that other operating systems such as Windows XP Home, Windows 9x, and DOS can't use dynamic disks, so if you intend to multiboot your machine, you should not upgrade the drive. Whether a drive is basic or dynamic has no bearing on network client access to shared folders.

If you don't seem to have the option of upgrading to dynamic disks, one of two possible reasons might be the cause. First, the disks may have already been upgraded to dynamic disks. Second, the disk is not a hard drive but rather a CD device or removable media device.

NOTE

You cannot install Windows XP onto a dynamic disk volume that you've added to a dynamic disk from another instance of Windows XP or Windows 2000. This is a limitation of the Windows XP Setup program in that it needs to see a partition table in order to install onto the disk. Disk partitions created from a dynamic disk do not contain partition tables and as such cannot be utilized by Setup. The only types of disks that contain partition tables are simple disks and dynamic disks that were upgraded from simple disks. However, you can convert the boot drive to a dynamic volume after installation has completed.

Extending a Disk

One of the really cool options available in the Disk Management is the option to extend a volume on a dynamic storage drive. Extending is really just another way of "stretching" a simple volume to a specified size when unallocated space is present on the disk. Sometimes you might want to rearrange the way you've set up your disks, so this option can come in very handy.

To perform the actual extend operation on a disk, you need to have an area of the disk that is unallocated. From there, you simply right-click an existing partition and select Extend Volume to bring up the Extend Volume Wizard. The wizard allows you to specify the size that you would like to extend the volume to. Finishing the operation leaves you with a disk that is now larger than before. This operation is not limited to volumes that are mounted as drive letters. You can also perform this task on volumes that are mounted into directories.

When Disk Management extends a disk, it is really just creating a new partition and mapping it to the same drive letter as the partition to be extended. It is, in effect, a spanned volume. Although this approach is a bit different from the traditional method performed by disk utilities such as Partition Magic, the upside of the Disk Management approach is that you can extend your disk without having to wait for the volume to be resized and data to be shuffled around. The Disk Management approach happens very quickly without even rebooting your system.

Creating a Spanned Volume

A spanned volume is a volume in which the disk space spans across multiple partitions and/or disks. Using a spanned volume is a very handy way of taking a couple of small disks and turning them into one large disk, mounted under one drive letter or folder. Simple volumes can also be extended using spanned volumes, as shown in the previous section. Spanned volumes can be created only on dynamic disks. A spanned volume basically is the same as an extended volume, except the former adds drive space from other hard drives while the latter adds drive space from the same drive.

Creating a spanned volume is just a matter of right-clicking an empty partition and selecting New Volume, which opens the New Volume Wizard. This wizard enables you to select the spanned volume option. Next, you are given the option to select which disks to include in your spanned volume. At this point, you also can select the amount of space to use for each disk. The total size of your spanned volume is the cumulative total of the space you select on each disk.

Finally, you are prompted for the mount point and the format for your new spanned volume.

Creating a Striped Volume

One of the procedures you can perform with Disk Management is creating a striped volume. Creating such a volume is often desirable simply because of the ease of administration as well as the substantial gain in speed. Creating a striped volume is really practical only if you're using more than one disk. In fact, you must have more than one disk. For the definition of a striped volume, see "Dynamic Storage" earlier in this chapter.

NOTE

Unfortunately for users, Microsoft decided to leave out the option to create RAID sets from Windows XP. This option, as well as mirroring, is included only in the Server and Advanced Server versions of what Microsoft is calling Windows Server 2003. You are not precluded from using a hardware-based RAID controller with Windows XP Professional and Home, however. In devices such as these, the BIOS is used to set up the RAID options, thereby bypassing the operating system.

When you're creating a striped volume, you are creating partitions of the same size across two or more disks. Bear this point in mind as you plan your implementation because you need to have the same amount of space available on each disk that you want to use for your set.

To create a striped volume, just follow these steps:

1.	Right-click one of the disks to be used in the striped volume set, and select New Volume. The New Volume Wizard then opens.
2.	Select Striped. Then select Next.
3.	Select the disks you want to include as part of a striped volume. The New Volume Wizard automatically selects the first free disk as the first in the striped volume. The remaining two disks can be selected from the left column and added to the right column for the set. When you are done adding disks, click Next. NOTE Notice that the wizard automatically sets the size for all selected disks to the largest amount of free space that is equally available on each disk.
4.	You then are prompted for the mount point of your new striped set. The three options here bear further explanation: Assign the Following Drive Letter This option assigns your set one drive letter like any normal drive. Selecting this option is the most common method of mounting a striped set, and it will suffice for most purposes. Mount in the Following Empty NTFS Folder This option is a bit different from anything previously offered in Windows. By mounting a striped set to a folder, you are effectively creating a mount point within another disk. The mount point isn't actually on another disk in the physical sense. The folder you use just has the amount of storage equal to the size of your striped set. This approach is more closely related to the UNIX approach, where the actual drive letter is not used but the folder is referred to as the mount point. (Mount points were discussed earlier in this chapter.) Do Not Assign a Drive Letter or Drive Path Selecting this option creates the striped set and leaves it for you to allocate at a later time using either of the two methods mentioned previously.
5.	Select the volume format options.
6.	When you are presented with a summary of the actions to be performed by the wizard, choose the Finish button so that your new striped volume will be created and mounted under the path you chose in step 4.

NOTE

In Explorer, notice that the icon for the folder mount point shows up as a hard disk. This icon appears simply so that you can differentiate between a mounted folder and a plain folder.

RAID and Dynamic Disk Information Storage

When a basic disk is made a member of a mirror, stripe, or RAID set, it's marked (or "signed") with a tiny hidden partition at the end of the disk drive. This partition tells Windows that the disk is a member of a fault-tolerant disk set. The information about the configuration itselffor example, whether a given disk is the primary or secondary disk in a mirror setis stored in the Registry. If you think about it, you can see that this is not a great place to store this kind of information: If a disk is damaged, Windows might not be able to read the Registry to find the configuration information. That's why you were always exhorted to update your Emergency Boot Disks when you made changes in the old Windows NT Disk Management; the disk configuration was stored on the emergency disks, too.

For dynamic disks, Windows creates a 4MB partition at the end of each disk drive in which it stores all the configuration information for all the dynamic drives in your computer. This redundant information helps Windows reconstruct a picture of the whole system if any drives are damaged or replaced, and it's another good reason to use dynamic disks over basic when you're building a Windows XP system.