Backing up and restoring a cluster

The appliance backup feature enables you to back up an appliance. You can restore the backed-up data when required. The backup can be made to the local file system, or to a remote destination over ssh or via a Windows share, so little local disk space is required. You can also choose to encrypt the backup. Security data is not included in a backup that is not encrypted. You can choose to be notified by email, if configured, of the completion and result (success or failure) of a backup task.

If you use appliance backup on a cluster, the entire cluster is backed up. If you choose to backup to local filesystem (the On Member option), each cluster member is backed up onto its local filesystem. When you backup a cluster to a remote destination, the appliance backup feature creates a single backup in which each machine's backup is contained in a subdirectory.

You can cancel an in-progress cluster backup, but only from original session on the UI of the machine from which the backup was started.

Important notices

Read and take note of the following notices before using the backup feature.

VMware snapshots and clusters

You can use the VMware snapshot tools to create a snapshot of all of the machines in a cluster. However, all machines must be shut down before starting the snapshot and must remain shut down until all of the snapshots are complete. This enables any internal cluster communication to be completed before the snapshot is created.

Destination system time must not be earlier than source when restoring a backup 

You must ensure that the current system time on the destination appliance is no earlier than that of the appliance on which the backup was created. If the modification times on the files contained in the backup are later than the system time when they are restored, the backup will hang. To recover at this point you must kill the backup process, correct the time, run tw_restore --fix-interrupted then repeat the restore using the tw_restore command line utility.

Backing up and CMDB synchronization

The backup contains the CMDB synchronization configuration. When a host has significantly changed so that its key has also changed, problems can be caused if a backup is restored before the changed host is rediscovered. In this case, on the next CMDB synchronization, duplicate hosts will be created in the CMDB representing the changed host, and the CIs representing the original hosts will never be deleted. To ensure that no duplicate hosts are created, you can delete and then recreate the BMC.ADDM dataset.

The backup contains the LDAP configuration. If the destination appliance cannot access the LDAP server, you must ensure that a local (non-LDAP) user belonging to the system and public groups is activated and successfully tested on the source appliance before making a backup.

If you choose to exclude the credential vault when backing up an appliance in which CMDB synchronization has been configured, the CMDB Sync page on the restored appliance displays the "This appliance has not been set up for synchronization with the Atrium CMDB" message. Once the Setup form is complete, filter and blackout window settings are restored.

Local backups 

We do not recommend using the On Members (local) backup option. The On Members backup type does not properly identify which member should receive which backup, and could result in service start failures after restore. You should use an SSH or SMB backup instead. See also the workaround (described below) that might be required for Windows share (SMB) backups.

Windows share (SMB) backups 

An OS level defect can prevent Windows share backups from completing. The verification step fails with the message "ERROR: Cannot read file ... Unexpected end of stream".

To workaround this problem:

1. Mount the share (that you want to backup to) on one of the cluster members, or on a spare Linux host.
2. Use SSH (or local) backup to the directory used to mount the Windows share.

Do not disable the verification step for Windows share backups. If you do so, and the backup fails because of this defect, you will receive no notification of the failure.

Backing up and restoring a cluster

The appliance backup feature replaces the appliance snapshot that was available in previous releases. On upgraded appliances only, if snapshots are still held in the filesystem, a banner and Remove Snapshots button is provided so you can remove the snapshots and release disk space.

During the backup, the services on all members of the cluster are shutdown for the backup and restarted when the backup is complete.

To create a backup of the cluster

1. From the main menu, click the Administration icon.  
   The Administration page displays.
2. In the Appliance section, click Backup & Restore.
   The Appliance Backup page opens. This has a panel in which you can configure the backup destination. It also shows details of the cluster size, the size of the backup for this member, and details of the contents of the backup.
   

3. Enter the details for the backup destination.

   The fields that can be completed are displayed or hidden depending on the backup type selection. Required fields are indicated with a red asterisk.

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4. Click Shutdown & Backup to start the cluster backup operation.
   You are prompted for confirmation.
5. Click No to return to the Appliance Backup page. Click Yes to continue and backup the appliance.
   All services are shut down on all members of the cluster for the backup and restarted when the backup is complete. During the backup, a progress window is displayed. A Cancel button is also displayed, but only on the UI for the machine from which the backup was started. The Cancel button is only enabled at the stages of the backup where it is possible to cancel.

To restore a backup to the cluster

1. From the Appliance section of the Administration tab, click Backup & Restore.
   The Appliance Backup page is displayed.
2. Click the Restore Backup tab.
   The Restore Backup tab has a panel in which you can choose the source of the backup, and provides details of the size and contents of the existing local backup.
   

3. Enter the details for the backup source.

   The fields that can be completed are displayed or hidden depending on the backup type selection. Required fields are indicated with a red asterisk.

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4. Click Shutdown & Restore to start the restore operation.
   You are prompted for confirmation.
5. Click No to return to the Appliance Backup page. Click Yes to continue and restore the cluster.
   All services are shut down on all members of the cluster for the restore and restarted when the restore is complete.

Accessing contents of an encrypted backup

You can access the contents of an encrypted backup on a cluster in the same way as for a standalone appliance. The backup held on each member is the backup for that member only; not for the cluster.