Converting a basic disk to dynamicWindows XP Setup and Disk Management ensures that disks initialized by Windows XP Professional can be converted to dynamic disks. Dynamic disks provide features that basic disks do not, such as the ability to create multidisk volumes, such as striped, mirrored, and RAID-5 volumes. Before you convert disks, close any programs that are running on those disks.
After you convert a basic disk into a dynamic disk, any existing partitions on the basic disk become (dynamic) simple volumes. You cannot change the dynamic volumes back to partitions.
Dynamic disks cannot be directly accessed by MS-DOS, Windows 95, Windows 98, Windows Millennium Edition, Windows NT, or Windows XP Home Edition, so you cannot start these operating systems on dynamic disks. However, shared folders on dynamic disks are available across a network to computers running all of these operating systems.
Access to dynamic disks is further restricted by the partition style used on the dynamic disk:
Only x86-based computers running Windows 2000 or Windows XP Professional, or Itanium-based computers running Windows XP 64-bit Edition can access dynamic MBR disks.
Only Itanium-based computers running Windows XP 64-Bit Edition can access dynamic GUID partition table (GPT) disks.
In order to successfully convert a basic disk to a dynamic disk:
Master boot record (MBR) disks must have at least 1 megabyte (MB) of free space at the end of the disk for the dynamic disk database. Disk Management and Setup automatically reserve this free space when creating partitions or logical drives on a disk, but disks with partitions or volumes created by other operating systems might not have this free space available. GUID partition table (GPT) disks do not require 1 MB of unallocated space at the end of the disk. Instead, Disk Management uses space from the Microsoft Reserved (MSR) partition to create a separate partition for the dynamic disk database.
GUID partition table (GPT) disks must have contiguous, recognized data partitions with Windows XP file systems on them. If an unrecognized partition (for example, created by another operating system or utility that used partition type GUIDs not supported by Windows XP 64-Bit Edition) exists between two recognized partitions, you cannot convert the GPT disk to dynamic.
The disk must not be removable media. You cannot convert removable media devices to dynamic volumes. Removable media devices can contain only primary partitions.
The disk must not be in a portable computer. Windows XP Professional and Windows XP do not support dynamic disks in portable computers.
The sector size must be 512 bytes. Otherwise, you cannot convert a basic disk to a dynamic disk. You can use the chkdsk command to determine the disk's sector size.
Other conversion considerations
Converting a basic disk to a dynamic disk also impacts the following:
Reinstalling Windows XP Professional. You can perform a fresh installation of Windows XP Professional on a dynamic volume only if that volume was converted from a basic volume and it retained an entry in the partition table. Simple volumes converted from basic disks on Windows XP Professional do not have an entry in the partition table unless they were system or boot volumes prior to conversion. This information is required to perform fresh installations of Windows XP Professional on dynamic volumes.
Boot and system partitions. You can convert a basic disk containing the system or boot partitions to a dynamic disk. After the disk is converted, these partitions become simple system or boot volumes (after restarting the computer). You cannot mark an existing dynamic volume as active. You can convert a basic disk containing the boot partition (which contains the Windows XP Professional operating system) to a dynamic disk. After the disk is converted, the boot partition becomes a simple boot volume (after restarting the computer).
Conversion failures. If you convert a boot disk, or if a volume or partition is in use on the disk you attempt to convert, you must restart the computer for the conversion to succeed. If any of the following conditions occur, the conversion can fail after the computer restarts:
If you disconnect all existing dynamic disks while the computer is restarting.
If you replace a disk or set of disks to be converted while the computer is restarting. (Disk Management detects that the disk has changed and the conversion may fail.)
If you change the disk layout of a disk to be converted.
If the disk has I/O errors during the conversion.
Mirroring the boot and system volumes. After you convert the disk containing the boot and system partitions to a dynamic disk, you can mirror the boot and system volumes onto another dynamic disk. Then, if the disk containing the boot and system volumes fails, you can start the computer from the disk containing the mirrors of these volumes.
When the conversion takes place. System and boot partitions are converted to dynamic volumes after the computer is restarted. All other partitions and basic volumes are converted immediately. However, if a partition or basic volume on the disk that you are converting is in use, an event known as "force dismounting" occurs, which means that any programs using the volume are automatically disconnected. If the volume cannot be force dismounted (for example, there is an active paging file on the volume), then the disk conversion does not complete until you restart the computer.
Other operating systems. If you convert a disk with a partition that contains an operating system other than Windows 2000 or Windows XP Professional, you will not be able to start the computer from that operating system after the conversion.
Reverting back to basic disks. After you convert a basic disk into a dynamic disk, you cannot change the dynamic volumes back to partitions. Instead, you must delete all dynamic volumes on the disk and then use the Convert To Basic Disk command.
For a description of the procedure for converting a basic disk into a dynamic disk, see To upgrade a basic disk to a dynamic disk.
