Dell Unity: Restoring Lost/Deleted Data from FS Snapshots for UNIX host (User Correctable)

Summary: Restoring deleted files/directories from a file system snapshot.

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Symptoms

Procedure to recover a snapshot from a snapshot hidden file by a UNIX host:
The first task for an NFS client is to connect to an NFS share on the file system. Access to the read-only snapshot is established by accessing the snapshots hidden .ckpt data path. This path will redirect the client to the point-in-time view that the read-only snapshot captures.

 

Cause

Deletion of some data from the file system

Resolution

1. List the exported file systems for the NAS Server:

[root@vhost fserver]# showmount -e <IP or FQDN of NAS Server>
Export list for fserver:
 

/NAS/exp            (everyone)
/exp                     (everyone)
/NASserver/exp/share  (everyone)
/share1                (everyone)
/share2                (everyone)
/share3                (everyone)

 

2. Create a Temp directory in any place:

[root@vhost fserver]# mkdir /mnt/test


3. Mount the root FS share onto the new Temp directory on the UNIX host. 

** Note: Only Root FS shares contain .ckpt hidden files. It cannot be a child share (e.g.: a share /NASserver/exp/share would not work)
 

[root@vhost fserver]# mount <IP or FQDN of NAS Server>:/share1 /mnt/test
[root@vhost fserver]# cd /mnt/test
[root@vhost fserver]# ls -la |grep -i .ckpt


...
~The output contains the snapshot file. Choose the .ckpt directory you want to restore data from.

.ckpt_2016_14_11_20.58.41_GMT
.ckpt_2016_15_11_20.58.41_GMT
.ckpt_2016_16_11_20.58.41_GMT
.ckpt_2016_17_11_20.58.41_GMT


4. Change the directory to the required .ckpt directory
 

[root@vhost fserver]#  cd .ckpt_2016_16_11_20.58.41_GMT
[root@vhost fserver]#  ls


This lists all the files/directories in the snapshot.

5. Copy the files to restore to the FS, or use the rsync command on UNIX.
 

[root@vhost fserver]# cp deletedfile /test

Additional Information

Because the read-only snapshot is exposed to the clients through the CVFS mechanism, the clients are able to directly recover data from the snapshot without any administrator intervention. For example, if a user either corrupted or deleted a file by mistake, that user could directly access the read-only snapshot and get an earlier version of the file from the snapshot and copy it to the file system to recover from.

Affected Products

Dell EMC Unity Family

Products

Dell Unity 300, Dell EMC Unity 300F, Dell EMC Unity 400, Dell EMC Unity 400F, Dell EMC Unity 500, Dell EMC Unity 500F, Dell EMC Unity 600, Dell EMC Unity 600F, Dell EMC Unity Family |Dell EMC Unity All Flash, Dell EMC Unity Family , Dell EMC Unity Hybrid, Dell EMC UnityVSA Professional Edition/Unity Cloud Edition ...
Article Properties
Article Number: 000052854
Article Type: Solution
Last Modified: 27 Jun 2025
Version:  3
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