Using Volume Shadow Copy (VSS) with DataKeeper/LifeKeeper for Windows Volumes
VSS Shadow Copy can be enabled for LifeKeeper for Windows-protected (shared or replicated) volumes. However, the following guidelines apply:
- VSS snapshot images must not be stored on a LifeKeeper for Windows-protected volume. Storing VSS snapshots on a LifeKeeper for Windows-protected volume will prevent LifeKeeper for Windows from being able to lock the volume and switch it over to another node.
- When a LifeKeeper for Windows-protected volume is switched or failed over, any previous snapshots that were taken of the LifeKeeper for Windows protected volume are discarded and cannot be reused.
- VSS snapshot scheduling is not copied between the LifeKeeper for Windows servers. If snapshots are scheduled to be taken twice a day on the primary server and a switchover occurs, this schedule will not be present on the backup server and will need to be redefined on the backup server.
- There is a slight difference in behavior when switching back to a server where snapshots were previously enabled:
- If the volume is a shared volume, VSS snapshots must be re-enabled.
- If the volume is a replicated volume, VSS snapshots are automatically re-enabled.
FAQ
- Will disabling the “Volume Shadow Copy service” affect LifeKeeper / DataKeeper?
-
Even with the service disabled LifeKeeper will still run the vssadmin command and when that occurs with you will get the following application event log error:
Volume Shadow Copy Service information: The COM Server with CLSID {e579ab5f-1cc4-44b4-bed9-de0991ff0623} and name Coordinator cannot be started. [0×80070422, The service cannot be started, either because it is disabled or because it has no enabled devices associated with it.]
Therefore, the service must be at least set to manual.
- Why are deep checks and quick checks running on the standby system?
When the check scripts run on the active node (source node of the mirror) the vssadmin commands are actually run on the target node(s) using the LifeKeeper command lcdremexec to perform the remote execution. This is why you see the Volume Shadow Copy Service start on the target node(s).
- Why is LifeKeeper running the command “vssadmin.exe delete shadows” at equal intervals and how to solve the problem?
For volume resources, LifeKeeper performs vssadmin commands via the vssadmin_wrapper.ksh during resource checks (quick/deep) and when taking the volume resource out of service. The vssadmin command as done as VSS shadow copy storage is not supported on mirrored or shared-disk volumes.
If VSS shadow copy storage is detected when taking a volume resource out of service it will fail the operation and manual steps must be taken to remove the shadow copy storage before the remove will be successful.
When the resource checks run (volume quickchk.ksh or deepchk.ksh scripts) it attempts to clean up any shadow copy storage on the target. The checks are done by default every 3 minutes (quickchk.ksh) and 5 minutes (deepchk.ksh) which is why the start occurs on a regular basis.
Solution: Unfortunately, there are no settings in LifeKeeper that can be made to change this behavior at this time.
Post your comment on this topic.