For system state backup on Windows Server, the system state data can only be spooled (temp drive) to the 'root' of a volume (e.g. D:, E:), the temp drive cannot be a 'sub-folder' of a volume
For a System State backup:
- The temp directory must be a local or USB drive (for 2008 R2 server, you may use a network drive but Microsoft does not 'officially' support backup to network path)
- If you are using a network path for the temp directory you must map the path to a drive letter. The backup to the temp drive must use the 'root' of a volume (e.g. D:, E:), the temp drive cannot be a 'sub-folder' of a volume
- The temp directory must be a NON-CRITICAL drive / volume
For spooling to a critical volume, you need to add a registry entry to allow spooling to any drive. Instruction can be found at:
The registry change above is only for System State backup, but not for System backup.
Note: According to Microsoft - "A volume is a critical volume if it contains system state information (system-critical components)", which includes the boot volume, the system volume or other volume with critical information (volume that contain the MS Exchange installation, MS SQL installation … etc).