Event ID 40 — Diff Area Integrity

Applies To: Windows Server 2008

The Diff Area is the storage space that Shadow Copies of Shared Folders allocates on a volume for maintaining the snapshots of the contents of shared folders. A snapshot is a block-level set of information that represents the differences between the current content and content from a previous point in time. The integrity of existing and new snapshots depends on the integrity of the Diff Area.

Event Details

Resolve

Fix problems with the volume that stores the Diff Area

You must use the chkdsk command to attempt to fix problems with the volume where the Diff Area is stored. If chkdsk reports that it was unable to correct an issue found on the volume, or if you continue to have problems with shadow copies, consider moving the Diff Area to a different volume.

To perform these procedures, you must have membership in Administrators, or you must have been delegated the appropriate authority.

Use chkdsk to fix problems with the volume where the Diff Area is stored

To fix volume problems using chkdsk:

1. Open an elevated command prompt. Click Start, point to All Programs, click Accessories, right-click Command Prompt, and then click Run as administrator.
2. Type chkdsk drive_letter**: /r** and press ENTER. drive_letter is the drive letter of the volume where the Diff Area is stored, as reported in the event log message.
3. If prompted whether you want to force a dismount of the volume, type N and press ENTER.
4. When prompted if you want to schedule the volume to be checked the next time the system restarts, type Y and press ENTER.
5. When practical, restart the computer to allow the volume to be checked and to correct any problems that are found.

Move the Diff Area to a different volume

To move the Diff Area to a different volume:

Caution: When you change the location of the Diff Area, all previous shadow copies are deleted. Follow this procedure only if you have already used chkdsk to check the volume where the Diff Area is stored and chkdsk reports that it was unable to correct an error found on the volume—or if shadow copies continue to fail.

1. Click Start, and then click Computer.

2. Right-click any of the volumes listed, and then click Configure Shadow Copies. If the User Account Control dialog box appears, confirm that the action it displays is what you want, and then click Continue.

3. Click the volume for which the shadow copy failed, and then click Settings.

   Note: If shadow copies of the volume are enabled, you must first disable them by clicking the volume, and then clicking Disable.

4. Set the Diff Area to a different volume by selecting a volume from the drop-down list under Storage area, and then click OK.

5. Verify that the volume is still selected and click Enable. If you are asked to confirm that you want to enable shadow copies, click Yes.

6. Click OK to exit.

Verify

The Diff Area is working correctly if a new shadow copy can be successfully created.

To perform this procedure, you must have membership in Administrators, or you must have been delegated the appropriate authority.

To create a new shadow copy:

1. Click Start, and then click Computer.

2. Right-click any of the volumes listed, and then click Configure Shadow Copies. If the User Account Control dialog box appears, confirm that the action it displays is what you want, and then click Continue.

3. Click the volume that you want to create a new shadow copy of, and then click Create Now. The Diff Area is working correctly if the new shadow copy is listed under Shadow copies of selected volume.

   Note: Depending on the size of the volume and the number of changes that have occurred since the last shadow copy, creating the new shadow copy can take a few seconds or several minutes.

Related Management Information

Diff Area Integrity

File Services