Generation Managed Differential Data Backup with SnapOPC+

This section describes operations that use the SnapOPC+ feature to periodically create a Volume Snapshot (Backup only incremental data). Create capacity-efficient backups on a regular basis. Saving only updates since the last backup saves drive usage compared to a full backup using QuickOPC.

Caution

  • Because only differential data is backed up, if data in an operation volume is corrupted due to a hardware failure, you cannot restore from Snapshot. A backup that is intended to recover from application errors or operational errors.

  • It is recommended to use QuickOPC in conjunction with the regular creation of a full backup to protect the operation volume from hardware failure.

RESTful API and Sample Scripts for Operation Use

  • Preparation

    Create a snapshot of the operation volume for several generations. Use snapopcplus_create.py.

  • Operation

    Periodically rotate Snapshots (delete the oldest Snapshot and create a new Snapshot) when you want to create backups. Use snapopcplus_rotate.py.

  • Restore

    Use POST /volume/{volume_id}/restore/{backup_volume_id} API to restore Snapshot data to an operation volume. For more information, see the description of Restoring from Clone or Snapshot.

  • Change in the number of generations

    If you want to increase the number of generations of Snapshots, use POST /volume/{volume_id}/snapshot API to add the Snapshot of the operation volume. If you want to reduce the number of generations, delete Snapshots by the number of generations to reduce, starting with the oldest Snapshot. Use snapopcplus_reduce.py to reduce the number of generations.

  • Deletion

    To remove all snapshots in an operation volume, use snapopcplus_delete.py.

Notes

  • Since SnapOPC+ is a copy-on-write method, Write I/O for uncopied space is worse than I/O performance for normal volumes. If the amount of updates is large, I/O performance to operation volume may degrade. If I/O performance degradation to an operation volume is unacceptable, backup with QuickOPC is recommended.

  • If Data Reduction is enabled for the Snapshot destination Thin Provisioning Pool, Data Reduction is also enabled for the created Snapshot by default. When Snapshot's Data Reduction is enabled, it includes deduplication and data compression in addition to copy, which can degrade I/O performance and copy performance to operation volumes. To reduce the performance impact on operation volumes, disable Data Reduction for Snapshots when creating Snapshots.

  • If an operation volume becomes inaccessible due to a hardware failure, the data in the generation-managed Snapshot cannot be read correctly.

  • The maximum number of Snapshots (number of generations) that can be created per operation volume is 512. When used in conjunction with other copy methods, fewer Backup Volumes can be created for an operation volume. For more information, see the description of multi-copy in "Available Advanced Copy Combinations" in "Design Guide".

  • If the Thin Provisioning Pool in which the Snapshot is created runs out of space, the Copy Session will fail and the Snapshot data will not be read correctly. To avoid this, periodically monitor the usage of the destination Thin Provisioning Pool.

  • If the SnapOPC or SnapOPC+ Copy Session fails, you will not be able to read the data in the destination region. In this case, delete and recreate the Snapshot.