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, when NetBackup services start, 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 to preserve data integrity. 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.  NOTE:  As of version 7.1, the DFSR writer is enabled at the time of the NetBackup Client install.

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 during the backup. All USN Journal updates are read by the DFSR engine during the backup period so no journal wrap issues occur. Once the backup is complete, NetBackup calls VSS to remove the snapshot and VSS will then call DFSR to 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. Use the following steps as a guide to configuring NetBackup to protect DFSR data in large environments.

Step 1: Create a global exclude entry for the top level DFSR “Shadow Copy Components:” path

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

“Add” and new global exclude entry for the absolute path to the top level “DfsrReplicatedFolders” path.

This will exclude the DFSR data path from “Shadow Copy Components:” backups for all policies that use ALL_LOCAL_DRIVES or “Shadow Copy Components:” directives. 

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

Open the DFSR Server’s “Client Host Properties” from the Master Server and add the following to a new Exclude List Entry.

Policy:  <<All Policies>>
Schedule:  <<All Schedules>>
Files/Directories:  Shadow Copy Components:\User Data\Distributed File System Replication\DfsrReplicatedFolders
 

Step 2: Create a dedicated policy for the DFSR Server

Create a unique policy for each DFSR server and note the name specified for the Policy as it will be required for Step 3.

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” field, specify the absolute path to each of the top level DFSR folder shares required for backup. 

To aid in determining the correct path to add to the File List directives for 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 node. 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.
 

For the DFSR policy File List Selection, use the example path below showing the top level DFSR path and append specific folders as required.

Example DFSR Path:
Shadow Copy Components:\User Data\Distributed File System Replication\DfsrReplicatedFolders\<Add Specific Folder>

Step 3: Create an Exception to the Exclude List entry for each DFSR Policy

In this step, it is required to create an Exception to the Exclude List for each DFSR policy so that the Shadow Copy Components” DFSR  paths are re-included for backup after the global exclude list is processed by NetBackup.

Open the DFSR Client “Host Properties” from the Master Server and add the following to a new “Exception to Exclude List” Entry. Be aware that the ‘Policy’ entry must match exactly the name and case sensitivity of the policy created in Step 2.

If DFSR is hosted in a cluster, repeat the steps to create the Exception to the Exclude List for each node in the cluster.

Policy: DFSR
Schedule: <<All Scheduled>>
Files/Directories: Shadow Copy Components:\User Data\Distributed File System Replication\DfsrReplicatedFolders

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
-  Use the NEW_STREAM directive when multistreaming backup selections. If this is not done, the result will be a status code 71.