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Shrink a Basic Volume

Applies To: Windows 7, Windows Server 2008 R2

You can decrease the space used by primary partitions and logical drives by shrinking them into adjacent, contiguous space on the same disk. For example, if you discover that you need an additional partition but do not have additional disks, you can shrink the existing partition from the end of the volume to create new unallocated space that can then be used for a new partition. The shrink operation can be blocked by the presence of certain file types; see Additional considerations for more information.

When you shrink a partition, any ordinary files are automatically relocated on the disk to create the new unallocated space. There is no need to reformat the disk to shrink the partition.

Membership in Backup Operators or Administrators, or equivalent, is the minimum required to complete this procedures.

CautionCaution
If the partition is a raw partition (that is, one without a file system) that contains data (such as a database file), shrinking the partition might destroy the data.

Shrinking a basic volume

To shrink a basic volume using the Windows interface
  1. In Disk Manager, right-click the basic volume you want to shrink.

  2. Click Shrink Volume.

  3. Follow the instructions on your screen.

    noteNote
    You can only shrink basic volumes that have no file system or use the NTFS file system.

Additional considerations

  • When you shrink a partition, certain files (for example, the paging file or the shadow copy storage area) cannot be automatically relocated and you cannot decrease the allocated space beyond the point where the unmovable files are located. If the shrink operation fails, check the Application Log for Event 259, which will identify the unmovable file. If you know the cluster or clusters associated with the file that is preventing the shrink operation, you can also use the fsutil command at a command prompt (type fsutil volume querycluster /? for usage). When you provide the querycluster parameter, the command output will identify the unmovable file that is preventing the shrink operation from succeeding.

    In some cases, you can relocate the file temporarily. For example, if the unmovable file is the paging file, you can use Control Panel to move it to another disk, shrink the volume, and then move the page file back to the disk.

  • If the number of bad clusters detected by dynamic bad-cluster remapping is too high, you cannot shrink the partition. If this occurs, you should consider moving the data and replacing the disk.

    Do not use a block-level copy to transfer the data. This will also copy the bad sector table and the new disk will treat the same sectors as bad even though they are normal.

  • You can shrink primary partitions and logical drives on raw partitions (those without a file system) or partitions using the NTFS file system.

To shrink a basic volume using a command line
  1. Open a command prompt and type diskpart.

  2. At the DISKPART prompt, type list volume. Make note of the number of the simple volume you want to shrink.

  3. At the DISKPART prompt, type select volume <volumenumber>. Selects the simple volume volumenumber you want to shrink.

  4. At the DISKPART prompt, type shrink [desired=<desiredsize>] [minimum=<minimumsize>]. Shrinks the selected volume to desiredsize in megabytes (MB) if possible, or to minimumsize if desiredsize is too large.

 

Value Description

list volume

Displays a list of basic and dynamic volumes on all disks.

select volume

Selects the specified volume, where volumenumber is the volume number, and gives it focus. If no volume is specified, the select command lists the current volume with focus. You can specify the volume by number, drive letter, or mount point path. On a basic disk, selecting a volume also gives the corresponding partition focus.

shrink

Shrinks the volume with focus to create unallocated space.

No data loss occurs. If the partition includes unmovable files (such as the page file or the shadow copy storage area), the volume will shrink to the point where the unmovable files are located.

desired= desiredsize

The amount of space, in megabytes, to recover to the current partition.

minimum= minimumsize

The minimum amount of space, in megabytes, to recover to the current partition. If you do not specify a desired or minimum size, the command will reclaim the maximum amount of space possible.

Additional considerations

  • When you shrink a partition, unmovable files (for example, the paging file or the shadow copy storage area) are not automatically relocated and you cannot decrease the allocated space beyond the point where the unmovable files are located. If you need to shrink the partition further, move the paging file to another disk, delete the stored shadow copies, shrink the volume, and then move the paging file back to the disk.

  • If the number of bad clusters detected by dynamic bad-cluster remapping is too high, you cannot shrink the partition. If this occurs, you should consider moving the data and replacing the disk.

    Do not use a block-level copy to transfer the data. This will also copy the bad sector table and the new disk will treat the same sectors as bad even though they are normal.

  • You can shrink primary partitions and logical drives on raw partitions (those without a file system) or partitions using the NTFS file system.

Additional references

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