Converting a basic disk to dynamic

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

Converting a basic disk to dynamic

Setup and Disk Management ensure that disks initialized by Windows Server 2003 operating systems 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. 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. The conversion may fail if you change the disk layout of a disk to be converted or if the disk has I/O errors during the conversion. 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.


  • If you are using a basic disk as a storage area for shadow copies and you intend to convert the disk into a dynamic disk, it is important to take the following precaution to avoid data loss. If the disk is a non-boot volume and is a different volume from where the original files reside, you must first dismount and take offline the volume containing the original files before you convert the disk containing shadow copies to a dynamic disk. You must bring the volume containing the original files back online within 20 minutes. Otherwise, you will lose the data stored in the existing shadow copies. If the shadow copies are located on a boot volume, you can convert the disk to dynamic without losing shadow copies.

    You can use the mountvol command with the /p option to dismount the volume and take it offline. You can mount the volume and bring it online using the mountvol command or the Disk Management snap-in.

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, Windows XP Professional, or Windows Server 2003 operating systems, and Itanium-based computers running the 64-bit version of Windows Server 2003, Enterprise Edition, or the 64-bit version of Windows Server 2003, Datacenter Edition, can access dynamic MBR disks.

  • Only Itanium-based computers, x86-based computers running Windows Server 2003 with Service Pack 1 (SP1), and x64-based computers can access dynamic GUID partition table (GPT) disks.

For instructions on how to convert a basic disk into a dynamic disk, see Change a basic disk into a dynamic disk.

For more information about dynamic disks and volumes, see Dynamic disks and volumes.