A backup fails out or gives a warning saying "Failed to create a snapshot for the local volumes ___" or something similar. Shortly afterward, in the backup job log, is a message saying "The VSS writer ___ is in a bad state." These errors either prevent the backup job from completing all tasks successfully or cause the backup job to fail right away. This error may occur every time the backup runs or may occur sporadically.
When Microsoft's Volume Shadow Copy service creates the shadow copies for a backup job, the VSS writers are involved in preparing their respective data for that process. If they cannot do this, the resulting shadow copy will be incomplete or inconsistent and will not be usable in the backup job.
In order for the backup to complete successfully, the shadow copy of volumes you intended to backup must be made which, in this case, may mean correcting the failed writer.
As with any VSS issue, it is first recommended you attempt to track down the VSS failure to either a "VSS" or "volsnap" error in the Application or System logs in Event Viewer, respectively. These events will more accurately reflect the nature of the VSS failure and allow you to troubleshoot the problem more effectively.
VSS writers may malfunction for any number of reasons, however, generally you can fix them by either restarting the service corresponding to the writer or rebooting the machine. To find out which VSS writers are in non-stable states, use the following command in an elevated command prompt:
vssadmin list writers
This should list the writer names, states, and last error. If any writer's state is something besides " Stable" then you may need to refresh that writer. To do this, first try restarting the service corresponding to the writer. Below is a list of common VSS writers and their respective services (this list is not exhaustive):
|VSS Writer||Service Name||Service Display Name|
|ASR Writer||VSS||Volume Shadow Copy|
|BITS Writer||BITS||Background Intelligent Transfer Service|
|COM+ REGDB Writer||VSS||Volume Shadow Copy|
|DFS Replication Service Writer||DFSR||DFS Replication|
|DHCP Jet Writer||DHCPServer||DHCP Server|
|FRS Writer||NtFrs||File Replication|
|FSRM Writer||srmsvc||File Server Resource Manager|
|IIS Config Writer||AppHostSvc||Application Host Helper Service|
|IIS Metabase Writer||SYSADMIN||IIS Admin Service|
|Microsoft Exchange Writer||MSExchangeIS||Microsoft Exchange Information Store|
|Microsoft Hyper-V VSS Writer||vmms||Hyper-V Virtual Machine Management|
|MSMQ Writer (MSMQ)||MSMQ||Message Queuing|
|MSSearch Service Writer||WSearch||Windows Search|
|NPS VSS Writer||EventSystem||COM+ Event System|
|NTDS||NTDS||Active Directory Domain Services|
|OSearch VSS Writer||OSearch||Office SharePoint Server Search|
|OSearch14 VSS Writer||OSearch14||SharePoint Server Search 14|
|Registry Writer||VSS||Volume Shadow Copy|
|Shadow Copy Optimization Writer||VSS||Volume Shadow Copy|
|SPSearch VSS Writer||SPSearch||Windows SharePoint Services Search|
|SPSearch4 VSS Writer||SPSearch4||SharePoint Foundation Search V4|
|SqlServerWriter||SQLWriter||SQL Server VSS Writer|
|System Writer||CryptSvc||Cryptographic Services|
|TermServLicensing||TermServLicensing||Remote Desktop Licensing|
|WIDW Writer||WIDWriter||Windows Internal Database|
|WINS Jet Writer||WINS||Windows Internet Name Service (WINS)|
|WMI Writer||Winmgmt||Windows Management Instrumentation|
If restarting the writer's service does not put the writer in a stable state or the service cannot be restarted, you may need to reboot the machine to fix the VSS writers. If a reboot does not fix them, consider re-registering the VSS writers or reinstalling the application that writer corresponds to.