Every Windows Administrator come across Backup Issues related to File Level Backup. We often see these issues are fixed mostly by reboot [as we all know Reboot fixes most of the issues] but it is hard to get the required Application\Server downtime to fix these issues. Also requesting the Server\Application owners for a reboot every now and then causes a lot of problem when it is caused on a single server more often.
We see most of the Backups are failed as one of the VSS writer is in Error\Failed or Waiting for Completion state. Reboot does fix these VSS writers and hence fixing the Backup Failure Issue.
What are these VSS Writers?
VSS Writers are Application Specific components designed by Microsoft [which is acronym of Volume Shadow Copy Service]. These Writers are compatible with various applications which helps in taking a complete snapshot of the data even though there are Ongoing Input\Output Transactions. This makes sure that there is no incomplete data collected. In the process if there are any transactions affecting the snapshot process the VSS writers may go into Error state hence causing Backup Failures. In this case most Administrators recommend rebooting the servers to fix this issue but there is a better way to decrease the downtime and fix the issue with the VSS writers by bringing them in stable state.
I have listed down few VSS writers and their associated Windows Services which can terminate the snapshot process and bring back the Writers in Stable state. Simply restart the below service if any VSS writer is in Error \ Failed or Waiting for Completion State.
| VSS Writer Name | Service Name | Service Display Name |
| ASR Writer | VSS | Volume Shadow Copy |
| BITS Writer | BITS | Background Intelligent Transfer Service |
| Certificate Authority | CertSvc | Active Directory Certificate Services |
| 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 | IISADMIN | IIS Admin Service |
| Microsoft Exchange Replica Writer | MSExchangeRepl | Microsoft Exchange Replication Service |
| Microsoft Exchange Writer | MSExchangeIS | Microsoft Exchange Information Store |
| Microsoft Hyper-V VSS Writer | vmms | Hyper-V Virtual Machine Management |
| MSMQ Writer | MSMQ | Message Queuing |
| MSSearch Service Writer | WSearch | Windows Search |
| NPS VSS Writer | EventSystem | COM+ Event System |
| NTDS | NTDS | Active Directory Domain Services |
| Registry Writer | VSS | Volume Shadow Copy |
| Shadow Copy Optimization Writer | VSS | Volume Shadow Copy |
| SMS Writer | SMS_SITE_VSS_WRITER | SMS_SITE_VSS_WRITER |
| SqlServerWriter | SQLWriter | SQL Server VSS Writer |
| System Writer | CryptSvc | Cryptographic Services |
| TermServLicensing | TermServLicensing | Remote Desktop Licensing |
| WMI Writer | Winmgmt | Windows Management Instrumentation |
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