Advanced Snapshots - SnapProtect for UNIX File System

Table of Contents

Managing Snapshots

The snapshots of the data created by the SnapProtect backup are also available for various other operations like list, mount, unmount, delete, or revert.

List Snapshots

The browse operation provides the capability to see the snapshots created for an agent, job, or a snapshot copy. The list of the snapshots displayed is corresponding to the entity selected for the browse operation, for e.g., browsing the snapshots for an agent will display all the snapshots created for the selected agent. You can view volume or disk related information for the snapshots. Follow the steps given below to browse snapshots.
  1. From the CommCell Browser, navigate to Client Computers | <Client> | <Agent> | <BackupSet>.
  2. Right-click the subclient and click List Snaps.

    The Snaps created during SnapProtect operation dialog box appears.

  1. The Snaps created during SnapProtect operation dialog box displays a list of all the snapshots created for the selected subclient. It also displays important information about each snapshot, including the source mount path, snap mount path, the storage array, and the source client.
    • Right-click the snapshot and click Details to view the snapshot properties.
    • Click the Disk View tab to display the snapshot name, e.g. SP_2_79_1286222629.

Mount Snapshots

You can mount any available snapshot to access the data included in the snapshot. Follow the steps below to mount snapshots:

When mounting multiple snapshots, note the following:

  • You can mount snapshots from different jobs
  • The snapshots selected for mounting should belong to the same iDataAgent, such as Unix file system, DB2 etc,.
  • The snapshots should be mounted on the corresponding OS MediaAgent. For example, Linux volumes should be mounted on a Linux MediaAgent etc,.
  • There are no limits on the number of snapshots to be mounted. However, if there are more number of snapshots selected, the time taken for mounting the snapshots also will increase.
  1. From the CommCell Browser, navigate to Client Computers | <Client> | <Agent> | <BackupSet>.
  2. Right-click the subclient and click List Snaps.

    The Snaps created during SnapProtect operation dialog box appears.

  1. Right-click the snapshot that you wish to mount and click Mount.

    To select multiple snapshots, hold <Shift> key and select the snapshots to be mounted.

  2. Click Yes.
  3. In the Mount Path dialog box, specify the destination client and the path on the client in the Destination Client and Destination Path fields.
  4. Click OK.

Cross-Platform Mounting of NFS Snapshots

When a client running a different UNIX operating system is used as a proxy for snap backup of NFS volumes, the NFS options might not be compatible across operating systems. In such cases, configure the following setting to skip the unsupported NFS options on the proxy client.

  1. From the CommCell Browser, navigate to Client Computers.
  2. Right-click the <Proxy Client>, and then click Properties.
  3. On the Client Computer Properties for <Proxy Client> dialog box, click Advanced.
  4. On the Advanced Client Computer Properties for <Proxy Client> dialog box, click the Additional Settings tab.
  5. Click Add.
  6. On the Add Additional Settings on Unix Client dialog box, perform the following:
    • In the Name box, type sSkipNfsOptions.
    • In the Category box, type iDataAgent.
    • In the Type box, type STRING.
    • In the Value box, type the NFS options to be skipped separated by a comma.

      For example: dev,forcedirectio,nodevices.

    • Click OK.
  7. Click OK to close the Advanced Client Properties dialog box.
  8. Click OK to close the Client Computer Properties for <Proxy Client> dialog box.
  9. Restart SnapProtect services on the proxy client.

Unmount Snapshots

Follow the steps given below to unmount snapshots:

  1. From the CommCell Browser, navigate to Client Computers | <Client> | <Agent> | <BackupSet>.
  2. Right-click the subclient and click List Snaps.

    The Snaps created during SnapProtect operation dialog box appears.

  1. Right-click the snapshot you wish to unmount and click Unmount.

    To select multiple snapshots, hold <Shift> key and select the snapshots to be mounted.

  2. Click Yes when prompted if you want to continue.

If the snapshot does not get unmounted, select the Force Unmount option to mark the snapshot as unmounted.

Delete Snapshots

Snapshots can either be deleted using job-based pruning or from the list of displayed snapshots when browsing snapshots. Data Aging can also be used to define the retention rules and pruning of snapshots. Follow the steps given below to delete snapshots:

  • Manual deletion of snapshots is not recommended. When a snapshot is deleted, it is no longer possible to perform data recovery operations from the snapshot copy. However, if a backup copy was created from the snapshot, data recovery operations can be performed from the backup copy.
  • Ensure that the snapshot to be deleted is not mounted.
  • For NetApp E-series PiT engine, the order to delete snapshots should be the oldest snapshot first.

  1. From the CommCell Browser, navigate to Client Computers | <Client> | <Agent> | <BackupSet>.
  2. Right-click the subclient and click List Snaps.

    The Snaps created during SnapProtect operation dialog box appears.

  1. Right-click the snapshot you wish to delete.

    Ensure all snapshots with the same Job ID are selected for a successful deletion operation.

  2. Click Delete.
  3. Enter the confirmation text string, erase snapshots.
  4. Click OK.

Force Delete

The force delete operation is useful when a client, subclient, or a storage policy copy has been deleted or when a source MediaAgent computer is unavailable and you want to delete snapshots from the CommCell database. The force-deleted snapshots are not moved to tape and are not deleted on the array.

  1. From the CommCell Browser, navigate to Client Computers | <Client> | <Agent> | <BackupSet>.
  2. Right-click the subclient and click List Snaps.

    The Snaps created during SnapProtect operation dialog box appears.

  1. Right-click the snapshot to select it to force delete.
  2. Click Force Delete.
  3. Enter the confirmation text string, force erase snapshots.
  4. Click OK.

Revert a Snapshot

You can use the revert operation to bring the data back to the point-in-time when the snapshot was taken. This operation overwrites any modifications to the data since the time when the snapshot was created. This option is available if the storage arrays that you are using supports revert. Revert operations are supported on NetApp File Servers but not from SnapVault or SnapMirror snapshots. You can either perform an application aware revert or a hardware specific revert.

Review the following before performing a revert operation:

  • Prior to performing a revert operation for ZFS LVM, consider the following:
    • The source Zpool should contain the same set of disks that were available during SnapProtect backup.
    • The entire Zpool will be reverted.
  • Revert operation is not supported for mirrored volumes.
  • Volumes to be reverted should not be monitored using DC. In case of LVM volumes, all the volumes in the volume group where the source volume resides should not be monitored using DC.
  • On Windows clients, disable automount using the following command:

    diskpart> automount disable

  • On Unix clusters, use pre/post scripts to freeze and unfreeze the cluster for revert operations. For example, on Red Hat Linux cluster, use the following command in the pre/post scripts:

    clusvcadm -Z <group> to freeze the cluster

    clusvcadm -U <group> to unfreeze the cluster

    This is required because during revert the application is shut down and corresponding volumes are unmounted. In that case, the cluster will automatically failover to another node thus preventing the revert operation.

  • It is recommended to verify the contents of the backup and ensure that you want to perform a revert operation as it is an irreversible operation.
  • If you plan to perform a revert operation, you will not be able to use the associated storage policy for further auxiliary copy operations.

Perform an Application Aware Revert

  1. From the CommCell Browser, right-click the entity that contains the data you want to restore, and click All Tasks | Browse Backup Data.
  2. From the Browse and Restore dialog box, click OK.
  3. Select the data you want to revert and click Recover All Selected.
  4. From the Restore Options dialog box, click Advanced.
  5. Select the Use hardware revert capability if available option.
  6. Click OK to confirm the revert operation.
  7. Click OK from the Advanced Restore Options dialog box.
  8. Click OK to start the revert.

    An application aware revert operation reverts back all the volumes included in the backup.

Perform a Hardware Specific Revert

  1. From the CommCell Console, navigate to Client Computers | <Client>.
  2. Right-click the subclient and click List Snaps.

    The Snaps created during SnapProtect operation dialog box appears.

  3. Right-click the snapshot that you wish to delete and click Use hardware revert capability if available.
  4. Enter the confirmation text string, confirm.
  5. Click OK.

A hardware specific revert operation reverts back the volume included in the snapshot. If the volume being reverted is the source of vault/mirror relation and if the protection topology is Primary-Vault, Primary-Mirror, or Primary-Vault-Mirror, then the baseline snapshot on primary volume will be shifted to the snapshot of the reverted volume. In case of Primary-Mirror-Vault or Primary-Mirror1-Mirror2 topologies, the baseline snapshot for Mirror-Vault relationship and Mirror1-Mirror2 relationship, respectively, is not shifted, which may lead to auxcopy job failures.

The revert operation might delete some snapshots. To avoid failures, when selecting SnapProtect jobs for auxcopy or backup copy operations, unpick all SnapProtect jobs that have deleted snapshots as a result of a revert operation. Running auxcopy or backup copy operations with SnapProtect jobs from deleted snapshots might produce failures.

Snap Reconciliation

Snapshots may be deleted from the array due to factors like low disk space on the array, number of snapshots exceeds the threshold etc., and the jobs corresponding to these deleted snapshots can no longer be used for any data recovery or backup copy operations. You can use the nRunSnapRecon additional setting to start snap reconciliation to check for missing snapshots once in every 24 hours and marks jobs corresponding to the missing snapshots as invalid.

Snap Cleanup

If a SnapProtect operation is in pending/suspended states or is killed, a prune request will be sent immediately and delete the snaps which were taken in that SnapProtect operation on the storage array. For example, if a SnapProtect operation is in pending state after taking snaps for data volume, then it will remove the snap for that data volume. Once the job resumes, it will take a snap again from data phase. As clean-up is performed immediately, you need not wait for the data aging job to remove un-useful snaps.

View Snapshot Details

You can view the details of a snapshot for an agent, job, or a snapshot copy. When you right-click any of these entities, you will be able to browse all the snapshots corresponding to the selected entity.
  1. From the CommCell Browser, right-click the entity that contains the snapshots you want to browse, and click All Tasks | List Snaps.
  2. The Snaps created during SnapProtect operation dialog box displays a list of all the snapshots created for the selected entity and displays important information about each snapshot, including the source mount path, snap mount path, the storage array, and the source client.
  3. Right-click the snapshot and click Details to view the snapshot properties.

Select a Job for Backup Copy

You can select a specific job for creating backup copy. Once selected, the Move Snap to Tape field for the specific job will be changed to Picked (i.e., the next backup copy operation will move this job to media).
  1. Right-click a storage policy containing SnapProtect backup jobs, and then click View Jobs.
  2. Right-click the job and then click Pick for Backup Copy.

Disable a Job for Backup Copy

You can prevent a job from being moved to media. You can apply this option to those jobs that were previously selected for moving to media. On selecting this option, the Move Snap to Tape field for the specific job will be changed to Not Picked (i.e., the next backup copy operation will not move this job to media).
  1. Right-click a storage policy containing SnapProtect backup jobs and then click View Jobs.
  2. Right-click the job and then click Do not Backup Copy.

SCSI Reservation

SCSI reservation can be enabled for SnapProtect backup for all the agents. Enabling SCSI Reservation prevents other applications (SCSI3 compliant) from using the reserved SCSI Device (i.e. the mounted snapshot).

If this option is enabled and the hardware does not support this type of operation, subsequent backup jobs may fail.

Use the following steps to enable SCSI reservation:

  1. From the CommCell Browser, navigate to Client Computers.
  2. Right-click the <Client>, and then click Properties.
  3. Click Advanced.
  4. Click the Additional Settings tab.
  5. Click Add.
  6. In the Name box, type nSCSIReserveForSnap.
  7. In the Category box, select iDataAgent.
  8. In the Type box, select Integer.
  9. In the Value box, type 1.