Backing up using the LUN method

This topic describes how to perform SAN File System backup operations using the LUN method. LUN backup requires that all transactions are stopped during the process.

Prerequisites

The LUN method of backup is only available to SANs comprised of storage subsystems with built-in copy services. SANs without such service must use the file-based (API) method of backup.

Context

Because the LUN method deals with data at the byte level, it is an all-or-nothing approach for backing up and restoring your entire SAN File System. In particular, it provides no ability to restore individual files (because it has no concept of files); you have to save and restore all the data — metadata and file data — or none of it. Restoring a previously saved FlashCopy® image is the best method for recovering some subset of SAN File System data. Therefore, the LUN method is best employed as part of a disaster recovery situation.

Steps

  1. Stop or pause all SAN File System client applications. Because this task is application-specific, refer to the application documentation for details on performing this step.
  2. The metadata server and all clients must complete all active transactions and flush their data to disk. From the master metadata server, quiesce the SAN File System metadata servers.
    /usr/tank/admin/bin/sfscli quiescecluster -state full

    This procedure will also lock out any subsequent new I/O from the clients or metadata server.

  3. Initiate the storage subsystem copy service using the procedure defined in its accompanying documentation.
  4. After the storage subsystem copy is complete, re-enable the SAN File System metadata servers.
    /usr/tank/admin/bin/sfscli resumecluster

    This procedure will also lock out any subsequent new I/O from the clients or metadata server.

  5. Restart the client applications using the specific procedures for those applications.

Result

For additional information about restore procedures, including commands, refer to the IBM® TotalStorage® SAN File System Maintenance and Problem Determination Guide, on the publications CD that came with your metadata servers.

Parent topic: Backing up the SAN File System

Parent topic: Managing backups

Related concepts
Backup and restore
Engines
FlashCopy images
Clients

Related reference
Managing disaster recovery

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