Backup and Restore of Microsoft DFSR data using Symantec NetBackup

Description

Backup and Restore of Microsoft DFSR data using Symantec NetBackup

About DFSR and NetBackup 

Distributed File System Replication (DFSR) is Microsoft's 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 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.  Replication is momentarily paused while the snapshot is being created.  The DFS Replication service remains started and is aware of all USN Journal updates. Once the snapshot is complete, replication resumes and the backup of data can commence.

Although it is possible to backup DFSR data as flat files with the 'DFS Replication' service stopped, this is not recommended by Symantec or Microsoft for several reasons.

  • Stopping DFS Replication for extended periods during a backup may allow the USN Journal to wrap thus causing replication failures.  
  • Backing up the DFSR files outside of the VSS Writer will include the replication database located within 'DfsrPrivate'.  If this data is restored, it will cause replication to fail.

 

Backup DFSR Data

NOTE: Strict rules for defining how to configure a NetBackup Policy to capture DFSR data do not exist.  However, we offer here some guidelines which may be adopted.

Policy Configuration – Small DFSR Environments ( <50 GB )

The simplest method to backup DFSR data 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 protect the all data on the client including the DFSR data which is protected as a component of “Shadow Copy Components”.




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 may be desired.

If this is the case, it is recommended to create 2 or 3 Policies to fit your needs:

Policy 1. Dedicated to backing up the non-DFSR data
Policy 2. Dedicated to backing up 
all DFSR data
Policy 3. Dedicated to backing up some-but-not-all DFSR data


Guidelines for setting up a Policy to backup the non-DFSR data

NOTE:  It is important to understand that by it self, the directive "Shadow Copy Components" will backup both DFSR data as well as the entire System State.  It is equally important to understand that System State does NOT include DFSR data.

1. Create an MS-Windows Policy and specify the DFSR Server as the client
2. Construct the Backup Selections by specifying the directive 'System State' and listing all the individual drive letters which exist on the client


NOTE: The above technique will protect the System State as well as all non DFSR data.  It will by omission, exclude DFSR data.


Guidelines for setting up a Policy to backup all DFSR data

1. Create an MS-Windows Policy and specify the DFSR Server as the client
2. Construct the Backup Selections by specifying the path to the root DFSR file path through Shadow Copy Components

NOTE: This path is very long and is prone to type-o's if manually typed.  Copy and paste the below path into the Backup Selections.  Be careful to not include a leading or trailing space character, as this will cause the backup selection to fail:


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

Example:

 


Guidelines for setting up a Policy to backup some DFSR data

NOTE: There may be situations where you wish to backup some-but-not-all of the DFS Replicated Folders on a replication partner.  Use the following technique to configure such a policy.

1. Create an MS-Windows Policy and specify the DFSR Server as the client
2. Construct the Backup Selections by specifying paths to the specific DFS Replicated Folders you wish to include
 

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 directory 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 (relaunch BA&R using Run As Administrator)
-- The DFS Replication service is stopped
-- If DFSR is clustered, the Backup, Archive and Restore GUI is run from the active node hosting DFSR
 



Restore DFSR Data

DFSR data that was backed up by NetBackup through Shadow Copy Components, will not be browsable on the Drive Letters of the resulting images.  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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