Event ID 21 — Volume Snapshot Driver Integrity
Applies To: Windows Server 2008
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Shadow Copies of Shared Folders uses the Volume Snapshot driver (Volsnap.sys) to create shadow copies in Windows. This driver uses storage space allocated on a volume to maintain a snapshot of the contents of the shared folders. This storage space is called the Diff Area.
Event Details
| Product: | Windows Operating System |
| ID: | 21 |
| Source: | VolSnap |
| Version: | 6.0 |
| Symbolic Name: | VS_MEMORY_PRESSURE_DURING_LOVELACE |
| Message: | The flush and hold operation for volume %2 was aborted because of low available system memory. |
Resolve
Monitor system resources
Determine if the computer is low on system resources like CPU resources, disk I/O performance, or memory. To identify what is causing the system to be low on resources, you can generate a System Diagnostics Report using Reliability and Performance Monitor, or you can use Resource Monitor to determine, in real-time, which applications or services are utilizing too many system resources.
To generate a System Diagnostics Report, which will present system information collected for 60 seconds, follow the steps in the "Generate a System Diagnostics Report" section. To use Resource Monitor to monitor system resources in real-time, follow the steps in the "Start Resource Monitor" section.
To perform these procedures, you must have membership in Administrators, or you must have been delegated the appropriate authority.
Generate a System Diagnostics Report
To collect system information for 60 seconds and generate a System Diagnostics Report:
- Open an elevated command prompt. Click Start, point to All Programs, click Accessories, right-click Command Prompt, and then click Run as administrator.
- Type perfmon /report and press ENTER. Reliability and Performance Monitor will start collecting data to create the System Diagnostics Report.
- When the report is ready for viewing, locate the Diagnostic Results section of the report and check for any Warnings. You can follow links for additional assistance on resolving warnings from this section. In addition, you can expand each category in the Basic System Checks section to see more details about why warnings appear. Also, the Performance section provides process-level detail about top resource consumers.
Start Resource Monitor
To start Resource Monitor:
Important: Resource Monitor stops collecting information while a System Diagnostics Report is being generated. To start collecting information after a System Diagnostics Report has completed, in Monitor, click Start.
- Open an elevated command prompt. Click Start, point to All Programs, click Accessories, right-click Command Prompt, and then click Run as administrator.
- Type perfmon /res and press ENTER. Resource Monitor will start running.
- Four scrolling graphs in the Resource Overview pane display the real-time usage of CPU, Disk, Network, and Memory. Four expandable sections below the graphs contain process-level detail about each resource. Click the resource labels to see more information, or click a graph to expand its corresponding details. You can use the real-time usage information to identify top resource consumers. Click a column heading to sort the data in the table by that column and click the column heading again to reverse the sort order.
Verify
The Volume Snapshot driver 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:
Click Start, and then click Computer.
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.
Click the volume that you want to create a new shadow copy of, and then click Create Now. The Volume Snapshot driver 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.