Data Migrator Administration Guide for Hitachi NAS Platform

Part Number

During migration, some data is on HNAS only, while other data is on the LNAS only. This makes backups/replications and subsequent recovery more complicated, and depends on the replication/backup mechanism that is used.

Ideally, the replication/backup of data on the HNAS and LNAS would be synchronized, such that the data contained in the pair of backups is guaranteed to be consistent. A consistent set could be guaranteed by the following method:

  1. Prevent client access to the data.
  2. Pause the migration by issuing the virtualization-path-control --pause command.
  3. Wait for activity to stop by issuing the virtualization-path-list command and wait until the counts displayed in the list stop changing.
  4. Take snapshots of the LNAS and HNAS and start the backup/replications of these snapshots.
  5. Allow client access.

This method can, however, be undesirable because you must prevent client access. A more acceptable alternative is to have time synchronized snapshots of the HNAS and LNAS to use for the replication/backups. This runs the risk of having inconsistencies between the LNAS and HNAS. You could mitigate this by pausing the background processes and/or ensuring the backups are done at a quiet time for client access.