On Windows Server 2008 R2, there are approximately 50,000 system state files, which use approximately 4 GB of disk space in the default installation of an x64-based computer. The fastest and easiest way to back up and restore a server’s system state is to use Wbadmin. With Wbadmin, you can use the START SYSTEMSTATEBACKUP command to create a backup of the system state for a computer and the START SYSTEMSTATERECOVERY command to restore a computer’s system state. (Note that when you select a system state restore on a domain controller, you have to be in the Directory Services Restore mode.) To back up a server’s system state, type the following at an elevated command prompt: 
wbadmin start systemstatebackup -backupTarget:VolumeName
Here VolumeName is the storage location for the backup, such as F:.
To restore a server’s system state, type the following at an elevated command prompt:
wbadmin start systemstaterecovery -backupTarget:VolumeName
Here VolumeName is the storage location that contains the backup you want to recover, such as F:.
Additionally, you can do the following:
- Use the –recoveryTarget parameter to restore to an alternate location.
- Use the –machine parameter to specify the name of the computer to recover if the original backup location contains backups for multiple computers.
- Use the –authSysvol parameter to perform an authoritative restore of the SYSVOL.
You can also recover the system state by using a backup that includes the system state or by performing a recovery.
From the Microsoft Press book Windows Server 2008 Administrator’s Pocket Consultant, Second Edition by William R. Stanek.