About NDMP with snapshots

Backup Administration Guide for Hitachi NAS Platform

Part Number

The server uses snapshots to backup data consistently and without being affected by on-going file activity.

The following options should be considered when planning a backup strategy:
  • Back up automatically created snapshots.

    When backing up a file system that is being actively updated, a snapshot of the file system is much more likely to produce a fully consistent image than backing up the live file system. As a result, NDMP is configured by default to automatically create a snapshot for backup.

  • Back up pre-created snapshots
    A backup can be taken from a specific snapshot that has been created by a rule or created spontaneously by user request:
    • To back up the latest snapshot created under a snapshot rule, use the environmental variable NDMP_BLUEARC_USE_SNAPSHOT_RULE.
    • To back up the latest snapshot created spontaneously by user request, request a specific snapshot by explicitly including the snapshot name in the path to back up. Where the path is based on a CIFS share name, indicate the snapshot using /~snapshot/snapshot_name; for paths based on an NFS export name, indicate the snapshot using/.snapshot/snapshot_name. CIFS shares and NFS exports may also include a snapshot name.
  • Backing up databases and iSCSI Logical Units

    The internal structures of Databases and iSCSI LUs are tightly coupled with the state of the client software (database manager/iSCSI Initiator) that is controlling the files. For example, backing up such files during a client operation may produce inconsistencies in the backup that would prevent recovery.

    Therefore, any backup of databases and iSCSI LUs must ensure that files are in a consistent state at the time of back up. Snapshots can be used to achieve this. Snapshot rules provide the most convenient mechanism, as this avoids having to explicitly specify the name of the snapshot used.
    Note: When configuring snapshot rules, ensure that snapshots have a sufficiently long shelf life, and before initiating a backup, verify that the snapshot is not scheduled to be replaced during the anticipated time of the backup, as such replacement would cause the backup to fail.

    For more information on backing up and restoring iSCSI LUs, refer to the File Services Administration Guide.