Working with Basic and Dynamic Disks

That's it, essentially, when it comes to the hows and whys of basic and dynamic disks. When it comes to using basic and dynamic disks, you'll perform several related tasks, such as initializing new disks, setting a drive as active, or changing the drive type. Before performing these tasks, however, you should understand what the active, boot, system, and other drive designations mean.

Understanding the Active, Boot, System, and Other Drive Designations

Whether working with basic or dynamic disks, you should pay particular attention to five special types of drive sections.

• Active The active partition or volume is the drive section from which an x86-based computer starts. When the computer uses multiple operating systems, the active drive section must contain the startup files for the operating system you want to start and it must be a primary partition on a basic disk. If you use Microsoft Windows NT, Windows 95, Windows 98, Windows Me, or MS-DOS, the active drive section should be the primary partition on Disk 0. If you use Windows 2000 or later, the active drive section can be a primary partition on a basic disk or a simple volume on a dynamic disk. The active partition is not normally marked as such in Disk Management. In most cases, it is the primary partition or the first simple volume on Disk 0. However, if you change the default configuration, you will see an Active label.

  Caution

  With removable media disks, you might see an Active status, which shouldn't be confused with the Active label associated with an active partition. Specifically, USB and FireWire card readers that use compact flash or other types of cards are displayed as having an Active status when media is inserted and the related drive is online. It is also important to note that in some cases, a removable media drive might be listed as Disk 0. In this case, you will need to look for the active partition on the first physical hard disk according to its disk number. For example, if the computer has Disk 0, Disk 1, and Disk 2, and the first physical disk in sequence is Disk 1, the active partition is most likely to be on the first primary partition on Disk 1.

• System The system partition or volume contains the hardware-specific (boot-strap) files needed to load the operating system. The system partition or volume can't be part of a striped or spanned volume. The system partition is labeled as such in the Status field of Disk Management's Volume List and Graphical views.

• Boot The boot partition or volume contains the operating system and its support files. On most systems, system and boot are the same partition or volume. Although it seems the boot and system partitions are named backward, this convention has been used since Windows NT was first introduced and has remained unchanged. Like the active partition, the boot partition is not normally marked as such in Disk Management. In most cases, it is the primary partition or the first simple volume on Disk 0. However, if the operating system is installed on a different partition or volume, you might see a Boot label.

• Page file A page file partition or volume contains a paging file used by the operating system. Because a computer can page memory to multiple disks, according to the way virtual memory is configured, a computer can have multiple page file partitions or volumes. However, depending on the service packs configured, the computer may only report the primary volume being used as a paging file.

• Crash dump The crash dump partition or volume is the one to which the computer attempts to write dump files in the event of a system crash. By default, dump files are written to the %SystemRoot% folder, but can be located on any desired partition or volume.

Each computer has one active, one system, one boot, and one crash dump partition or volume. The page file designation is the only drive designation that you might see on multiple partitions or volumes.

Installing and Initializing New Physical Disks

Windows Vista makes it much easier to add new physical disks to a computer. After you install the disks following the disk manufacturer's instructions, you need to log on and start Disk Management. If the new disks have already been initialized, meaning they already have disk signatures allowing them to be read and written to, they should be brought online automatically if you select Rescan Disks from the Action menu. If you are working with new disks that have not been initialized, meaning they don't have disk signatures, Disk Management will start the Initialize And Convert Disk Wizard as soon as it starts up and detects the new disks.

You can use the Initialize And Convert Disk Wizard to initialize the disks by completing the following steps:

1. Click Next to exit the Welcome page. On the Select Disks To Initialize page, the disks you added are selected for initialization automatically, but if you don't want to initialize a particular disk, you can clear the related option.

2. Click Next to display the Select Disks To Convert page. This page lists the new disks as well as any nonsystem or boot disks that can be converted to dynamic disks. The new disks aren't selected by default. If you want to convert the disks, select them and then click Next.

3. The final page shows you the options you've selected and the actions that will be performed on each disk. If the options are correct, click Finish. The wizard then performs the designated actions. If you've elected to initialize a disk, the wizard writes a disk signature to the disk. If you've elected to convert a disk, the wizard converts the disk to a dynamic disk after writing the disk signature.

If you don't want to use the wizard, you can close it and use Disk Management instead to view and work with the disk. In the Disk List view, the disk will be marked with a red icon that has an exclamation point, and the disk's status will be listed as Not Initialized. You can then right-click the disk's icon and then select Initialize Disk. Confirm the selection (or add to the selection if more than one disk is available for initializing) and then click OK to start the initialization of the disk.

Marking a Partition as Active

You don't normally need to change a partition's designation. If you are using only Windows Vista or if you are multibooting to Windows Vista and any other Windows-based operating system, you do not have to change the active partition. On an x86-based computer, the active partition typically is the primary partition or the first simple volume on Disk 0. If you install Windows Vista on drive C and Windows 2000 or later on a different partition, such as drive D, you don't need to change the active partition to boot Windows Vista or the other operating system. However, if you want to boot a non-Windows operating system, you typically must mark its operating system partition as active and then reboot to use this operating system.

Note

Only primary partitions can be marked as active. You can't mark logical drives as active. You can't mark volumes as active. When you upgrade a basic disk containing the active partition to a dynamic disk, this partition becomes a simple volume that's active automatically.

To mark a partition as active, complete the following steps:

1. Make sure that the necessary startup files are on the primary partition that you want to make the active partition. For Windows NT, Windows 2000, and Windows XP, these files are Boot.ini, http://www.Ntdetect.com, Ntldr, and Bootsect.dos. You might also need Ntbootdd.sys.

2. Start Disk Management by typing diskmgmt.msc at an elevated command prompt.

3. Right-click the primary partition you want to mark as active and then select Mark Partition As Active.

Caution

If you mark a partition or volume as active, Disk Management might not let you change the designation. As a result, if you restart the computer, the operating system might fail to load. The only workaround I've found is to use DiskPart to make the appropriate changes either before rebooting or before using the startup repair tool following a failed start.

Listing 1 shows a sample DiskPart session for setting the active partition. As you can see, when you first start DiskPart, it shows the DiskPart program name and the version you are using, as well as the name of the computer. You then select the disk you want to work with and list its partitions. In this example, you select Disk 0 to work with, list its partitions, and then select partition 1. Once you've selected a disk and a partition on that disk, you can work with that partition. Simply typing the ACTIVE command at this point and pressing Enter sets the partition as active. When you are finished, you quit DiskPart using the EXIT command.

Note

This example uses Disk 0. On your system, Disk 0 might not be the one you want to work with. You can use the LIST DISK command to list the available disks and then use the information provided to determine which disk to work with.

Listing 1: Using DiskPart to Set the Active Partition

C:>diskpart

Microsoft DiskPart version 6.0.5782
Copyright (C) 1999-2007 Microsoft Corporation.
On computer: ENGPC85

DISKPART>      select disk 0

Disk 0 is now the selected disk.

DISKPART>  list partition

    Partition  ###    Type               Size       Offset
    -------------    ----------------    -------    -------
    Partition 1       Primary            176 GB     32 KB

DISKPART>      select partition 1

Partition 1 is now the selected partition.

DISKPART>      active

DiskPart marked the current partition as active.

DISKPART>  exit

Converting a Basic Disk to a Dynamic Disk and Vice Versa

The easiest way to convert a basic disk to a dynamic disk and vice versa is to use Disk Management. When you upgrade to a dynamic disk, partitions are automatically changed to volumes of the appropriate type. Any volume sets created under Windows NT are created as spanned or striped volumes as appropriate. Any primary partitions will become simple volumes. Any logical drives in an extended partition will become simple volumes. Any unused (free) space in an extended partition will be marked as Unallocated. You can't change these volumes back to partitions. Instead, you must delete the volumes on the dynamic disk and then change the disk back to a basic disk. Deleting the volumes destroys all the information on the disk.

Before you convert a basic disk to a dynamic disk, there are several important considerations. You should ensure that you don't need to boot the computer to a previous version of Windows. You should also ensure that the disk has 1 MB of free space at the end of the disk. Although Disk Management reserves this free space when creating partitions and volumes, disk management tools on other operating systems might not; as a result, the conversion will fail. It is also important to note the following restrictions:

• You can't convert drives that use sector sizes larger than 512 bytes. If the drive has large sector sizes, you'll need to reformat before upgrading.

• You can't convert removable media to dynamic disks. You can configure removable media drives only as basic drives with primary partitions.

• You can't convert a disk if the system or the boot partition is part of a spanned or striped volume. You'll need to stop the spanning or striping before you perform the conversion.

Note

You can convert disks with other types of partitions that are part of spanned or striped volumes. These volumes become dynamic volumes of the same type. However, you must convert all drives in the set together.

To convert a basic disk to a dynamic disk, complete the following steps:

1. In Disk Management, right-click a basic disk that you want to convert, either in the Disk List view or in the left pane of the Graphical view. Then select Convert To Dynamic Disk.

2. In the Convert To Dynamic Disk dialog box, select the check boxes for the disks you want to convert, as shown in Figure 1. If you're upgrading a striped volume originally created on Windows NT, be sure to select all the basic disks in this set. You must convert the set together.

   
   Figure 1: Select the basic disk to convert.

3. If the disk you are converting has no formatted volumes, clicking OK converts the disk, and you do not need to follow the remaining steps. If the disk you are converting has formatted volumes, clicking OK displays the Disks To Convert dialog box, and you need to follow the remaining steps to complete the conversion.

4. The Disks To Convert dialog box shows the disks you're converting so you can confirm the conversion. Notice the value in the Will Convert column, which should be Yes as long as the disk meets the conversion criteria, and then click Details to see the volumes on the selected drive. When you are ready to continue, click OK to close the Convert Details dialog box.

5. To begin the conversion, click Convert. Disk Management warns you that once you convert the disk, you won't be able to boot previous versions of Windows from volumes on the selected disks. Click Yes to continue.

6. Next you are warned that file systems on the disks to be converted will be dismounted, meaning they will be taken offline and be inaccessible temporarily. Click Yes to continue. If a selected drive contains the boot partition, the system partition, or a partition in use, Disk Management will need to restart the computer and you will see another prompt.

To convert a dynamic disk to a basic disk, complete the following steps:

1. Before you can change a dynamic disk to a basic disk, you must delete all dynamic volumes on the disk. Because this destroys all the data on the volumes, you should back up the volumes and then verify the backups before making the change.

2. When you are ready to start the conversion process, start Disk Management. In Disk Management, right-click the disk you want to convert and select Convert To Basic Disk. This changes the dynamic disk to a basic disk, and you can then create new partitions and logical drives on the disk.