Working with Basic and Dynamic Disks

Windows Server 2008 supports two types of disk configurations:

  • Basic The standard disk type used in previous versions of Windows. Basic disks are divided into partitions and can be used with previous versions of Windows.
  • Dynamic An enhanced disk type for Windows Server 2008 that you can update without having to restart the system (in most cases). Dynamic disks are divided into volumes and can be used only with Windows 2000 and later releases of Windows.

Note You can't use dynamic disks on portable computers or with removable media.

Using Basic and Dynamic Disks

When you convert to Windows Server 2008, disks with partitions are initialized as basic disks. When you install Windows Server 2008 on a new system with unpartitioned drives, you have the option of initializing the drives as either basic or dynamic.

Basic drives support the standard fault-tolerant features. You can use basic drives to maintain existing spanning, mirroring, and striping configurations and to delete these configurations. However, you can't create new fault-tolerant drive sets using the basic disk type. You'll need to convert to dynamic disks and then create volumes that use mirroring or striping. The fault-tolerant features and the ability to modify disks without having to restart the computer are the key capabilities that distinguish basic and dynamic disks. Other features available on a disk depend on the disk formatting.

You can use both basic and dynamic disks on the same computer. The catch is that volume sets must use the same disk type. For example, if you have mirrored drives C and D that were created under Windows NT 4.0, you can use these drives under Windows Server 2008. If you want to convert C to the dynamic disk type, you must also convert D. To learn how to convert a disk from basic to dynamic, see "Changing Drive Types" on page 348.

You can perform different disk configuration tasks with basic and dynamic disks. With basic disks, you can do the following:

  • Format partitions and mark them as active
  • Create and delete primary and extended partitions
  • Create and delete logical drives within extended partitions
  • Convert from a basic disk to a dynamic disk

With dynamic disks, you can do the following:

  • Create and delete simple, striped, spanned, mirrored, and RAID-5 volumes
  • Remove a mirror from a mirrored volume
  • Extend simple or spanned volumes
  • Split a volume into two volumes
  • Repair mirrored or RAID-5 volumes
  • Reactivate a missing or offline disk
  • Revert to a basic disk from a dynamic disk (requires deleting volumes and reloading)

With either disk type, you can do the following:

  • View properties of disks, partitions, and volumes
  • Make drive letter assignments
  • Configure security and drive sharing

Special Considerations for Basic and Dynamic Disks

Whether you're working with basic or dynamic disks, you need to keep in mind five special types of drive sections:

  • Active The active partition or volume is the drive section for system cache and -startup. Some devices with removable storage may be listed as having an active partition.
  • Boot The boot partition or volume contains the operating system and its support files. The system and boot partition or volume can be the same.
  • Crash Dump The partition 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.
  • Page File A partition containing 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.
  • System The system partition or volume contains the hardware-specific files needed to load the operating system. The system partition or volume can't be part of a striped or spanned volume.

Note On an x86-based computer, you can mark a partition as active using Disk Management. In Disk Management, right-click the primary partition you want to mark as active, and then select Mark Partition As Active. You can't mark dynamic disk volumes as active. When you convert a basic disk containing the active partition to a dynamic disk, this partition becomes a simple volume that's active automatically.

Changing Drive Types

Basic disks are designed to be used with previous versions of Windows. Dynamic disks are designed to let you take advantage of the latest Windows features. Only computers running Windows 2000 or later releases of Windows can use dynamic disks. However, you can use dynamic disks with other operating systems, such as UNIX. To do this, you need to create a separate volume for the non-Windows operating system. You can't use dynamic disks on portable computers.

Windows Server 2008 provides the tools you need to convert a basic disk to a dynamic disk and to change a dynamic disk back to a basic disk. When you convert to a dynamic disk, partitions are changed to volumes of the appropriate type automatically. 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.

Converting a Basic Disk to a Dynamic Disk

Before you convert a basic disk to a dynamic disk, you should make sure that you don't need to boot the computer to other versions of Windows. Only computers running Windows 2000 and later releases of Windows can use dynamic disks.

With MBR disks, you should also make sure 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. Without the free space at the end of the disk, the conversion will fail.

With GPT disks, you must have contiguous, recognized data partitions. If the GPT disk contains partitions that Windows doesn't recognize, such as those created by another operating system, you can't convert to a dynamic disk.

With either type of disk, the following holds true:

  • 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 converting.
  • You can't use dynamic disks on portable computers or with removable media. You can only configure these drives as basic drives with primary partitions.
  • You can't convert a disk if the system or boot partition is part of a spanned, striped, mirrored, or RAID-5 volume. You'll need to stop the spanning, mirroring, or striping before you convert.
  • You shouldn't convert a disk if it contains multiple installations of the Windows operating system. If you do, you might be able to start the computer only using Windows Server 2008.
  • You can convert disks with other types of partitions that are part of spanned, striped, mirrored, or RAID-5 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, follow these 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. If you're converting a spanned, striped, mirrored, or RAID-5 volume, be sure to select all the basic disks in this set. You must convert the set together. Click OK to continue.
  3. The Disks To Convert dialog box shows the disks you're converting. The buttons and columns in this dialog box contain the following information:
    • Name Shows the disk number.
    • Disk Contents Shows the type and status of partitions, such as boot, active, or in use.
    • Will Convert Specifies whether the drive will be converted. If the drive doesn't meet the criteria, it won't be converted, and you might need to take corrective action, as described previously.
    • Details Shows the volumes on the selected drive.
    • Convert Starts the conversion.
  4. To begin the conversion, click Convert. Disk Management warns you that after you finish the conversion you won't be able to boot previous versions of Windows from volumes on the selected disks. Click Yes to continue.
  5. Disk Management will restart the computer if a selected drive contains the boot partition, system partition, or a partition in use.

Changing a Dynamic Disk Back to a Basic Disk

Before you can change a dynamic disk back to a basic disk, you must delete all dynamic volumes on the disk. After you do this, right-click the disk and select Convert To Basic Disk. This changes the dynamic disk to a basic disk; you can then create new partitions and logical drives on the disk.

Reactivating Dynamic Disks

If the status of a dynamic disk displays as Online (Errors) or Offline, you can often reactivate the disk to correct the problem. You reactivate a disk by following these steps:

  1. In Disk Management, right-click the dynamic disk you want to reactivate, and then select Reactivate Disk. Confirm the action when prompted.
  2. If the drive status doesn't change, you might need to reboot the computer. If this still doesn't resolve the problem, check for problems with the drive, its controller, and the cables. Also make sure that the drive has power and is connected properly.

Rescanning Disks

Rescanning all drives on a system updates the drive configuration information on the computer. Rescanning can sometimes resolve a problem with drives that show a status of Unreadable. You rescan disks on a computer by selecting Rescan Disks from Disk Management's Action menu.

Moving a Dynamic Disk to a New System

An important advantage of dynamic disks over basic disks is that you can easily move them from one computer to another. For example, if after setting up a computer, you decide that you don't really need an additional hard disk, you can move it to another computer where it can be better used.

Windows Server 2008 greatly simplifies the task of moving drives to a new system. Before moving disks, you should follow these steps:

  1. Open Disk Management on the system where the dynamic drives are currently installed. Check the status of the drives and ensure that they're marked as healthy. If the status isn't healthy, you should repair partitions and volumes, as necessary, before you move the disk drives. Note Drives with BitLocker Drive Encryption cannot be moved using this technique. BitLocker Driver Encryption wraps drives in a protected seal so that any offline tampering is detected and results in the disk being unavailable until an administrator unlocks it.

  2. Check the hard disk subsystems on the original computer and the computer to which you want to transfer the disk. Both computers should have identical hard disk subsystems. If they don't, the Plug and Play ID on the system disk from the original computer won't match what the destination computer is expecting. As a result, the destination computer won't be able to load the right drivers, and boot might fail.

  3. Check whether any dynamic disks that you want to move are part of a spanned, extended, or striped set. If they are, you should make a note of which disks are part of which set and plan on moving all disks in a set together. If you are moving only part of a disk set, you should be aware of the consequences. For spanned, extended, or striped volumes, moving only part of the set will make the related volumes unusable on the current computer and on the computer to which you are planning to move the disks.

When you are ready to move the disks, follow these steps:

  1. On the original computer, start Computer Management. Then, in the left pane, select Device Manager. In the Device list, expand Disk Drives. This shows a list of all the physical disk drives on the computer. Right-click each disk that you want to move and then select Uninstall. If you are unsure which disks to uninstall, right-click each disk and select Properties. In the Properties dialog box, click the Volumes tab and then choose Populate. This shows you the volumes on the selected disk.
  2. Next, select the Disk Management node in Computer Management on the original computer. Right-click each disk that you want to move and then select Remove Disk.
  3. After you perform these procedures, you can move the dynamic disks. If the disks are hot-swappable and this feature is supported on both computers, remove the disks from the original computer and then install them on the destination computer. Otherwise, turn off both computers, remove the drives from the original computer, and then install them on the destination computer. When you're finished, restart the computers.
  4. On the destination computer, access Disk Management and then select Rescan Disks from the Action menu. When Disk Management finishes scanning the disks, right-click any disk marked Foreign and then click Import. You should now be able to access the disks and their volumes on the destination computer.

Note In most cases, the volumes on the dynamic disks should retain the drive letters that they had on the original computer. However, if a drive letter is already used on the destination computer, a volume receives the next available drive letter. If a dynamic volume previously did not have a drive letter, it does not receive a drive letter when moved to another computer. Additionally, if automounting is disabled, the volumes aren't automatically mounted and you must manually mount volumes and assign drive letters.

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