Backup and Restore of Microsoft DFSR data using Symantec NetBackup

Article:HOWTO65638  |  Created: 2012-01-05  |  Updated: 2014-04-28  |  Article URL http://www.symantec.com/docs/HOWTO65638
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Backup and Restore of Microsoft DFSR data using Symantec NetBackup

About DFSR and NetBackup 

Microsoft Distributed File System Replication (DFSR) service is a multi-master block level replication engine that is used to keep folders synchronized on multiple servers. Once DFSR is configured on a Windows Server host, NetBackup will detect the DFSR instance and make two changes to ensure data consistency during backups. First, the folders used to host the Shared Replica DFSR data become automatically excluded by NetBackup from normal Windows File System backups. Second, the top level DFSR shared folders become a part of the “Shadow Copy Components”. NetBackup utilizes the Microsoft VSS DFSR Writer to consistently snap the volumes hosting DFSR data.  

Although it is possible to backup Microsoft DFSR data as ‘flat files’ with the replication engine services stopped, this is not recommended by Symantec or Microsoft. Stopping replication for extended periods during a backup may cause USN Journal wrap. DFSR should recover from the issue but in large deployments, very long delays may occur before replication synchronizes and normal replication is resumed.

Current releases of NetBackup are able to backup DFSR data while the replication engine is active by using the VSS DFSR Writer API. During the backup, NetBackup call VSS to create a snapshot for the backup. As part of the DFSR snapshot process, VSS also calls for a pause in DFSR replication allowing the DFSR engine to remain running but not replicating while NetBackup uses VSS to take a snapshot. All USN Journal updates are read by the DFSR engine during the backup period so no journal wrap issues occur. Once the snapshot is complete, DFSR will resume normal replication.


Backup DFSR Data

Policy Configuration – Small DFSR Environments ( <50 GB )

For small environments, the simplest method to backup DFSR data on a Windows Server is to create an MS-Windows policy, select “ALL_LOCAL_DRIVES” as the Directive for the Backup Selection and specify the DFSR Server as the Client. No other configuration actions are needed. NetBackup will include the DFSR Data automatically in the “Shadow Copy Components:” portion of the backup.
 

This configuration will perform a backup of all drives and ‘Shadow Copy Components’ which includes all DFSR Data on the server.


Policy Configuration – Medium to Large DFSR Environments (>50 GB)

In larger environments, the amount of data managed by DFSR may not allow for timely backups of “Shadow Copy Components” and a more granular backup strategy is required. It is recommended to create a policy dedicated to backing up exclusively DFSR data.


Step 1: Create a policy-specific exclude against DFSR data for all non-DFSR specific policies

From the NetBackup Master server, open the Host Properties of each DFSR Server used to host DFSR Data.

“Add” a new policy specific exclude entry for the absolute path to the DFSR
 data: 
Shadow Copy Components:\User Data\Distributed File System Replication\DfsrReplicatedFolders

This will exclude the DFSR data path from “Shadow Copy Components:” backups for the specified Policy.

Note: If DFSR is in a cluster, add the same exclude entries to each node of the cluster.


Step 2: Create a dedicated policy for the DFSR data

Create a unique policy for each DFSR server.

For DFSR Servers hosted in a cluster, specify the DFSR Cluster instance hostname in the “Clients’ tab instead of the local node.

In the “Backup Selections” tab of the Policy, if you wish to backup all the DFSR data, simply add a path to the root of the DFSR directive.

Example:
Shadow Copy Components:\User Data\Distributed File System Replication\DfsrReplicatedFolders

 

If however, you wish to omit some DFSR content, you can choose to add paths to specific replicated folders, but not others:

Example:
Shadow Copy Components:\User Data\Distributed File System Replication\DfsrReplicatedFolders\LosAngeles
Shadow Copy Components:\User Data\Distributed File System Replication\DfsrReplicatedFolders\NewYork
Shadow Copy Components:\User Data\Distributed File System Replication\DfsrReplicatedFolders\Denver

To aid in determining the correct path(s) to add to the Backup Selections of the DFSR backup policy, open the Backup, Archive and Restore GUI on the DFSR Server, then ‘Select for Backup’ to open the file browser. 

Navigate down the Shadow Copy Components tree to the DfsrReplicatedFolders level. This will provide the exact path to each top level DFSR folder as seen by NetBackup.


As you navigate down the backup tree, the selected path will be displayed in the ‘Contents of” status bar. Move down the tree structure into “Shadow Copy Components:”  to view all unique DFSR Folders being hosted. It is important to note that these paths are unique to each DFSR server being protected by NetBackup.
 

Troubleshooting Note:

If the “User Data” node is not visible in the Backup, Archive and Restore GUI, confirm that the following are correct:

-- NetBackup Client Service has sufficient permissions to the server
-- DFSR services are active
-- If DFSR is clustered, the Backup, Archive and Restore GUI is run from the active node hosting DFSR
-- Registry value from TechAlert TECH53332 (Formerly Technote 290900) to backup DFSR offline has been removed



Restore DFSR Data

DFSR data that was backed up by NetBackup with DFSR Service active at the time of backup will not be located on the Drive path that hosts the replicated folders. DFSR data is located under “Shadow Copy Components:\User Data\Distributed File System Replication\DfsrReplicatedFolders:”.

To restore DFSR Data, open the Backup, Archive and Restore GUI and browse down the “Shadow Copy Components:\User Data\DfsrReplicatedFolders” path for the files to recover.  Select and restore files as normal files.

 


Alternate path restores are supported by NetBackup.
“Overwrite existing files” must be selected prior to starting the restore.
During restore, the redirected path is appended to the beginning of the DFSR path.


For example, if “C:\DFSR-Restore” is used as the Alternate path, the following will be the result of the restore.

Backup path:
Shadow Copy Components:\User Data\Distributed File System Replication\DfsrReplicatedFolders\DFSR-Data

Alternate path after restore:
C:\DFSR-Restore\DfsrReplicatedFolders\DFSR-Data

 

* Known Restrictions:

 - Excludes within the DFSR hierarchy are not supported  - All Versions
 - Duplicate Folder Names within the same DFSR configuration are not supported in versions 6.5.4, 6.5.5 and 7.0
 - There is a path limit of 256 characters  in versions 6.5.4, 6.5.5 and 7.0





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