Restoring SnapVault data to the primary storage system

In the event of data loss on a primary storage system, you might need to restore data from the secondary storage system.

Considerations

Restoring data from the SnapVault secondary storage system involves the following command-line operations.

You use the snapvault restore command to restore a backed-up qtree saved to the secondary storage system. Starting with Data ONTAP 7.3, you can restore the data to an existing qtree on the primary storage system using baseline restore or incremental restore.
- Baseline restore: The primary storage system must be running Data ONTAP 7.3 or later, and the secondary storage system can be running any Data ONTAP version.
- Incremental restore: Both the primary and secondary storage systems must be running Data ONTAP 7.3 or later.
Note: Starting with Data ONTAP 7.3, the SCSI connectivity of applications to all LUNs within the qtree being restored will be maintained throughout the restore process in order to make the restore operation non-disruptive to applications. However, I/O operations will not be allowed during the restore operation. Only in-place baseline restores and incremental restores can be non-disruptive.
After successfully restoring data, you use the snapvault start -r command to resume the SnapVault relationship between the restored qtree and its backup qtree on the secondary storage system (because you want to continue SnapVault protection of the data). If you do not want to continue the backup relationship, you use the snapvault release command to cancel any further backups of the restored qtree and to release the resources on the secondary storage system that were used in the SnapVault relationship.

When several SnapVault restore operations to different primary qtrees in the same volume are being run concurrently, Snapshot cleanup might fail due to Snapshot copies being locked by various restore operations. Therefore, some unwanted Snapshot copies are left behind in the volume.
Workaround: You can manually delete these unwanted Snapshot copies. Make sure that you do not delete the base Snapshot copy of the restore operation.

Note: If you do not want to resume the relationship, you can delete the Snapshot copy created by the restore operation. If you want to resume the SnapVault operation, you can delete the Snapshot copy after you have successfully resumed the relationship.

To restore data from the SnapVault secondary storage system to the primary storage system, complete the following steps.

Steps

If you intend to restore a primary qtree to the exact qtree location on the primary storage system from which you backed it up, you can perform any one of the following steps:
- Baseline restore—The baseline restore can be to an existing qtree or to a non-existing qtree.
  Note: In case of a baseline restore to an existing qtree, the restore operation overwrites the qtree data.
- Incremental restore—The restore operation transfers only incremental changes from the secondary qtree to the specified primary qtree.
Note: When you want to restore over an existing primary qtree, it is recommended that you first attempt an incremental restore. If the incremental restore fails due to lack of common Snapshot copies, then attempt an in-place baseline restore. This is because the incremental restore is a more efficient restore.
Enter the following command on the primary storage system on a single line:snapvault restore [-f] [-k n] [-r] [-w] [-s snapname] -S sec_system:sec_qtree_path [prim_system:]prim_qtree_path
-S [sec_system:]sec_qtree_path specifies the secondary storage system and qtree path from which you want to restore the data.

The -f option forces the command to proceed without first asking for confirmation from the user.

The -k option sets the maximum transfer rate in kilobytes per second.

The -r option attempts an incremental restore. The incremental restore can be used to revert the changes made to a primary storage system qtree since any backed-up version on the secondary storage system. Because it transfers only the required changes from the secondary storage system to the primary storage system, it is more efficient than a baseline restore.

The -w option causes the command not to return after the baseline transfer starts. Instead, it waits until the transfer completes (or fails). At that time, it prints the completion status and then returns.

The -s option specifies that the restore operation must be from snapshot snapname on the secondary storage system.

prim_system is the name of the primary storage system that you want to restore to. If specified, this name must match the name of the host system.

prim_qtree_path is the name of the primary storage system qtree that you want to restore to.

For options to the snapvault restore command, see the na_snapvault(1) man page.

If you want to...	Then...
Resume SnapVault backups of the newly restored qtree on the primary storage system	Go to Step 4.
Discontinue the backup relationship between the newly restored qtree on the primary storage system and its secondary qtree partner	Go to Step 6.

To resume the SnapVault relationship between the restored qtree and its backup qtree on the secondary storage system, enter the following command on a single line: snapvault start -r [options] -S [prim_system:]prim_qtree_path [sec_system:]sec_qtree_path
-r is required to restart backups from a restored primary storage system. For details about the snapvault command syntax, see the na_snapvault(1) man page .
You have finished. See Example 1.
To discontinue the SnapVault relationship between the restored qtree and its backup qtree on the secondary storage system, enter the following command on the secondary storage system:snapvault release sec_qtree_path [prim_system:]prim_qtree_path
sec_qtree_path is the name of the secondary storage system qtree that you want to release from a SnapVault relationship.

[prim_system:]prim_qtree_path is the name of the primary storage system qtree that you want to release.
You have finished.

Examples of restoring SnapVault data
The following examples show how to restore SnapVault data on the primary storage system.
Deleting the residual Snapshot copy
When you use the snapvault restore command to restore a primary qtree, SnapVault places a residual SnapVault Snapshot copy on the volume of the restored primary qtree. This Snapshot copy is not automatically deleted. If you have configured this volume to retain the maximum 251 Snapshot copies allowed by Data ONTAP, you must manually delete this residual Snapshot copy, or else no new Snapshot copies can be created.

Parent topic: Data protection using SnapVault