MS SharePoint backups depend on 3 VSS writers:
- SharePoint Services Writer (in MS SharePoint 2013, it is disabled by default and needs to be registered)
- OSearch VSS Writer
You can check the availability of these writers through a system console, for example the Command Prompt:
vssadmin list writers
When there is difficulty starting or completing a SharePoint backup, it often helps to troubleshoot the writers.
What to do if a writer is unavailable
If one of the writers is unavailable (missing from the response to
vssadmin list writers), you can try some typical solutions before contacting support.
|Name of missing writer||Possible solutions|
|SharePoint Services Writer||
|OSearch VSS Writer||Activate the SharePoint Server Search 14 service that handles the writer.|
Checking the statuses of VSS writers
The VSS writers are activated through appropriate services. If any of the writers are not available, please start the Services Console and make sure the following services are available and their statuses are as follows:
- Volume Shadow Copy – must not be disabled
- SharePoint Server Search 14 – must not be disabled
- SQL Server VSS Writer – Started and set to the Automatic startup type
- SharePoint VSS Writer – Started and set to the Automatic startup type
Registering the SharePoint Services Writer
In MS SharePoint 2010 and 2013, you may need to register the SharePoint Services Writer in the Windows registry.
Sometimes the writer can be enabled but not participating in backups. In that case, it needs to be disabled and then enabled again.
Here are steps to follow:
- Start the Command Prompt (cmd.exe)
- Go to the BIN directory
- MS SharePoint 2010:
cd "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\BIN"
- MS SharePoint 2013:
cd "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\15\BIN"
- MS SharePoint 2010:
- From the BIN directory, run the appropriate command:
Identifying spaces in the names of SQL databases
The names of SQL databases for MS SharePoint must not start or end with a space (this is crucial for successful backups). You can check it in the following way:
- In SQL Server Management Studio, right-click on any database. Select Run query
- From sys.databases, run the following query:
select '#' + name +'#'
If detected, the spaces must be removed.
Granting SQL Server VSS Writer access to the database
Sometimes the access permissions granted to the SQL Server VSS Writer may be insufficient. This can happen in the following cases:
- The Writer is running under a user with insufficient privileges
- The Writer does not have sufficient privileges to access the database
Here is how to resolve the issue:
- Add permissions for the NT AUTHORITY/SYSTEM service logon and any user which you have mentioned as service logon
- Check SQL server security attributes for the user selected as service logon for SQL writer and add sysadmin privileges
Instructions on restoring data from this data source can be found on Recovering data in Backup Manager.