Replibit uses the 'volume shadow copy' (VSS) technology built in to Windows to safely perform backups of open files. VSS provides the functionality to take a snapshot of a volume, allowing backups to backup data from the unchanging snapshot instead of the volume that is changing all the time.
***The Microsoft Volume Shadow copy Service is a standard Windows service and not installed by Replibit. The Replibit Agent and Replibit backups cannot cause VSS to fail, it simply uses the service. If you are receiving backup failures which point to VSS, it is caused by other software or system configuration problems and will affect every program that uses VSS.***
VSS has three parts that work together:
- VSS Providers: Providers implement the logic to actually take and maintain a snapshot of a volume. Windows comes with a default provider authored by Microsoft. It works with any volume so long as there is at least one volume in the system that is formatted with NTFS. Expensive NAS/DAS devices may provide their own hardware-based VSS provider.
- VSS Writers: Writers represent server applications that need to flush cached data to disk before a snapshot is taken, so that the snapshot represents good, consistent data. Both Exchange 2003 (or better) and SQL Server 2000 (or better) provide VSS writers. Many times problems with VSS are caused by the failure of some application-specific writer, outside the control of the backup application.
- VSS Requestor: Requestors represent applications that need to make, release, and use snapshots. For example, a backup application.
When a Replibit backup fails, the problem is almost always caused by the failure of the Microsoft VSS provider or one of the application-specific VSS writers. The C:\Program Files (x86)\Replibit/aristos.log log should contain informational messages that could give more information about which provider or writer failed.
You should inspect the Windows application and system logs (Start, run, eventvwr) for any vss, volsnap, or other entries around the time when the backup started. The error number and the word VSS can often be used in a web search to find specific information about the possible causes of the error. You should consider events from applications whose VSS writer has failed. For example, if the backup log indicates that the Exchange writer failed, then you should also look for Exchange events in the Windows event log.
You should use the information in the logs to troubleshoot before trying any repair steps. Find the error and search for it on the web. Chances are you will find the resolution faster this way and will have issue resolved without the need following the below steps. This will save you hours of work.
You should run the following commands at a command prompt to see the status of the providers and writers in your system, and whether any are in a failed state:
vssadmin list providers vssadmin list writers
If you see any providers or writes in a failed state, reboot the system and run them again to see if it clears up the error. If it does then try another backup. If the backup still fails with VSS issue try the next steps.
- In step One, if you see any third party providers from other backup applications, you will need to uninstall the applications. After they are uninstalled check again. If they are still there open regedit and look at “HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\VSS\Providers”. Under that key you should find the third party key which should be exported and then deleted.
- Reboot and run Step One
- Clean up any old Shadows by entering this at the cmd prompt
- vssadmin delete shadows /all
- Reboot and run Step One
You should also try applying any Microsoft hotfixes and updates that are related to VSS
Beyond these steps how to resolve the problem is usually very specific and related to the specific VSS provider or writer failure. Many others on the web have usually encountered the same error. Searching for the VSS error code listed in the backup log (usually begins with 0x8.......) along with VSS and/or the name of the VSS writer will usually find relevant information. Our support team is also able to assist you in finding solutions to failures in your VSS providers and writers.
When you contact our support team please send them the backup log showing the VSS errors, any related errors and events from the windows event log, and the output of the vssadmin commands listed above. This will help our team find the resolution for your specific failure. The types of failures are very diverse and very specific, so the more information you provide the better our support team will be able to assist you.