Slow backup throughput is observed while backing up the Windows System Partition and System State of a Windows 2008/Windows Vista Operating System. The slowness is mainly observed while the "System Root\Windows" directory is being backed up.
IMPORTANT NOTE: This issue has been addressed in Backup Exec 12.5 Service Pack 2 and Backup Exec 2010 as well.
1. In Windows Vista and Windows Server 2008, the default locations for user data and system data have changed.
There are junction points that are used to provide file and registry virtualization in Windows Vista and Windows Server 2008 and they can be divided into two classes: per-user junctions and system junctions.
By unchecking the options mentioned in the workaround below, Backup Exec spends less time on these junction points to avoid:
* Back up the same data more than once.
* Cycles (circular references) caused by these junction points.
2. System state files have increased in number and size.
3. With newer operating systems there are more number of Exclusion Rules that a backup software has to process adding to the time taken for a backup of a system volume.
4. The VSS snapshot backup of the System Volume of a Windows 2008 server shows less byte count than a Non-snapshot backup of the same volume, in the event that the VSS service is disabled. (Note: For Windows 2008 server, do not disable the VSS service)
The reason the VSS backup of the System Volume reports a smaller byte count is because with VSS enabled, all the system related files that are protected as part of the SYSTEM STATE resource are excluded from the System Volume backup. As a result the resultant byte count from the System Volume backup is lesser than a non-snapshot backup where these system files do not get excluded.
If the System Volume and the System State resources are backed up together in one backup job, the effective byte count by adding up the byte count from the individual resources will match that of the total used space on the System Volume. This behavior will be seen only while backing up the System Volume on a Windows 2008 Server.
How does the backup of Windows 2008 resources with BEWS work?
Backup Exec for Windows Servers leverages the Microsoft Volume Shadow Copy Service (VSS) by default to protect Windows 2008 resources.
Please refer to Microsoft Developer Network documentation for more details on the VSS framework.
Should the backup throughput rate be compared between Windows Server Backup (wbadmin) with that of Backup Exec for Windows Servers?
Backup throughput rates of volume backups may not be compared with those of Backup Exec for Windows Servers.
Because Windows Server Backup uses Volume Shadow Copy Service (VSS) and block-level backup technology to back up and recover your operating system, files and folders, and volumes.
However a comparison of the System State backup throughput rate may be done between Windows Server Backup and Backup Exec for Windows Servers.
1) Backup the windows partition with the following settings :
Uncheck the following options under Backup Job Properties | Advanced |
Back up files and directories by following junction points
Back up files and directories by following symbolic links (unchecked by default)
It is strongly recommended that all the volumes and system state be regularly backed up in preparation for disaster recovery.
For Backup Exec 12.5:
2) Upgrade to Backup Exec 12.5 Service Pack 4.
Symantec Corporation has acknowledged that the above-mentioned issue is present in earlier versions of the product(s) cited at the end of this article. Symantec Corporation is committed to product quality and satisfied customers.
There are no plans to address this issue by way of a patch or hotfix in earlier versions of the software at the present time. However, the issue has been addressed in the revision of the product specified at the end of this article.
Please contact your Symantec Sales representative or the Symantec Sales group for upgrade information including upgrade eligibility to the release containing the resolution for this issue. For information on how to contact Symantec Sales, please see <http://www.symantec.com>