During periods of high I/O activity, your Windows Server 2003 logs the follow event in the Application event log:
Event Type: Error
Event Source: VolSnap
Event Category: None
Event ID: 25
Description: The shadow copies of volume
This behavior may occur if the computer has run out of shadow copy storage space and/or the Volsnap.sys driver has encountered excessive I/O activity, causing the diff area to not grow.
To workaround this behavior, try any of the following:
- Install SP1 (Service Pack 1) or later.
- If there is insuffient shadow copy storage space, increase the space.
- Add another hard disk volume exclusively for shadow copy storage.
- Adjust the diff area size to 5 percent of the smallest shadow copy storage space on any one volume on the system, but not less than 600 or greater than 3000. Open a CMD.EXE window and type:
REG ADD HKLM\SYSTEM\CurrentControlSet\Services\VolSnap /V MinDiffAreaFileSize /T REG_DWORD /F /D- If you continue to receive event ID 25, place the shadow copy storage on another partition, even if it has to be on the same disk. Make sure it is not on the same partition as the paging file.