When you break a software mirrored RAID volume by using the Diskpart tool, the Windows Server 2003 System event log records:

Event Type: Error
Event Source: Volsnap
Event Category: None
Event ID: 8
Date: MM/DD/YYYY
Time: HH:MM:SS
User: N/A
Computer: <ComputerName>
Description: The flush and hold writes operation on volume C: timed out while waiting for a release writes command.

This behavior is caused by a problem in the DmAdmin service (Logical Disk Manager Administrative Service).

The event does NOT indicate a problem, and can be safely ignored.

NOTE: See How do I turn on logging to troubleshoot the Windows Server 2003 VDS (Virtual Disk Service)?