How to Resize a Volume

New in Windows Vista, and also included in Windows 7, is the ability to expand and contract simple volumes without a third-party tool. You can also expand and contract spanned volumes, but striped volumes are fixed in size. To change the size of a striped volume, you need to delete and re-create it.

Note Third-party products offer additional flexibility in resizing partitions, allowing the resizing of partitions with no available unallocated space immediately adjacent to the partition that you want to extend and also allowing you to control the placement of the unallocated space after shrinking the partition.

To shrink a volume, follow these steps:

1. Open the Disk Management snap-in.
2. Right-click the volume you want to shrink and then click Shrink Volume.
3. The Shrink dialog box opens and shows the maximum amount by which you can shrink the volume in megabytes. If desired, decrease the amount to shrink the volume and then click Shrink. The shrink process will proceed without further prompting.

You can also use DiskPart interactively from an elevated command line, using exactly the same steps as you would use with a script. The following interactive steps show how to shrink a volume as much as possible.

DiskPart

  Microsoft DiskPart version 6.1.7100
  Copyright (C) 1999-2008 Microsoft Corporation.
  On computer: WIN7
  DISKPART list volume

DISKPART> list volume

DISKPART> select volume 4

  Volume 4 is the selected volume.

DISKPART> shrink querymax

  The maximum number of reclaimable bytes is: 26 GB

DISKPART> shrink

  DiskPart successfully shrunk the volume by: 26 GB

Note In the code list, the command shrink querymax queries the volume to determine the maximum amount of shrinkage that the volume will support. The actual number will depend on the amount of free space on the volume, the fragmentation level, and where critical files are located on the volume.

To extend a volume, the steps are similar:

1. Open the Disk Management snap-in.
2. Right-click the volume you want to extend and then click Extend Volume. The Extend Volume Wizard appears.
3. Click Next. The Select Disks page appears.
4. Select the disks and set the amount of space from each disk to include in the extended volume. If you are extending a volume on a basic disk and you choose noncontiguous unallocated space or space on a second disk, the extension will also convert any disks involved to dynamic disks as part of the extension. Click Next.
5. On the Completing The Extend Volume Wizard page, click Finish. If the extension requires conversion to a dynamic disk, you'll see a warning.