Data Domain: How to Restore Deleted Files from an Existing MTree Snapshot

Summary: This article provides instructions on how to restore deleted files from an existing MTree snapshot.

This article applies to This article does not apply to This article is not tied to any specific product. Not all product versions are identified in this article.
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Symptoms

Data Domain Restorers (DDRs) hold backup data in files within the Data Domain file system (DDFS). It is possible that files may be removed due to:
  • User error
  • Defects within backup applications
  • Incorrect settings within backup applications
  • Disgruntled employees, cyber attacks, ransomware spreading across the network, and so forth
It is possible to create point in time snapshots of the contents of the Data Domain file system. Be aware that:
  • In version 4.x of the Data Domain Operating System (DDOS), a snapshot contains the contents of the entire Data Domain file system at the point in time the snapshot was created
  • In version 5.x of DDOS and later, a snapshot contains the contents of a single MTree within the Data Domain file system at the point in time the snapshot was created
If accidental file deletion occurs, it is possible to recover data from a point in time snapshot (assuming a snapshot containing a copy of the deleted data exists).

From here on, all information pertains to MTree level snapshots, as present in DDOS 5.x and later releases.

Cause

Restore deleted files from an existing MTree snapshot.

Resolution

The following steps should be taken to recover accidentally deleted data from a point in time snapshot:
  1. Determine if any snapshots exist on the system and the point in time at which each snapshot was created:
# snapshot list mtree [mtree name]
For the snapshot to contain a copy of the deleted data, it must have been:
  • Created after the point in time the data was written to the DDR
  • Created before the point in time the data was accidentally deleted
  • Created against the MTree from which data was accidentally deleted
For further information about listing snapshots on a DDR, see the article Data Domain - How to List Snapshots.
  1. Use the filesys fastcopy command to retrieve deleted files from the point in time snapshot. Each snapshot has a subdirectory by its name under the (hidden) ".snapshot/" directory directly below the root for the corresponding MTree path. That is, for an MTree named "MTREE" and a snapshot named "SNAPSHOT," the path would be "/data/col1/MTREE/.snapshot/SNAPSHOT/":
# filesys fastcopy [update] source [file/directory in snapshot] destination [destination file/directory]
For example, let us say a user has accidentally deleted the following file: /data/col1/backup/testfolder/test1.txt
They have determined that there is a snapshot against the backup MTree which, given the time at which the snapshot was created, holds a copy of test1.txt - the snapshot is named 'snap1'.

The following command would be used to restore the file: 
# filesys fastcopy source /data/col1/backup/.snapshot/snap1/testfolder/test1.txt destination /data/col1/backup/testfolder/test1.txt
Retrieved files do not have to be copied back to their original MTree. As a result, the user may decide to restore test1.txt to the /data/col1/new mtree: 
# filesys fastcopy source /data/col1/backup/.snapshot/snap1/testfolder/test1.txt destination /data/col1/new/test1.txt
In addition, entire directories can be restored from snapshots in a single command. In this case, the entire /data/col1/backup/testfolder directory is retrieved from the snapshot: 
# filesys fastcopy source /data/col1/backup/.snapshot/snap1/testfolder destination /data/col1/backup/testfolder
This overwrites the existing contents of /data/col1/backup/testfolder so the existing contents of this directory are lost (if the destination directory exists, it is overwritten with the contents of the directory from the snapshot)

The filesys fastcopy command has two (hidden) options, which are force and update, which are described in more detail in the article Data Domain: An explanation of 'filesys fastcopy force' and 'filesys fastcopy update' commands available on a Data Domain Restorer (DDR)
  1. Once data has been retrieved from the snapshot, either browse to the destination directory or use backup application functionality to ensure that the data is visible and available once more.

Additional Information

 

 

Affected Products

Data Domain

Products

Data Domain
Article Properties
Article Number: 000060023
Article Type: Solution
Last Modified: 04 Jul 2024
Version:  3
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