HNAS NDMP file replication and tape backups

Data Migrator Administration Guide for Hitachi NAS Platform

Part Number

Because object-based backup is incompatible with virtualization, file based replication must be used. The recovery of data from the HNAS backup, following damage to the live HNAS file system, has to encompass a manual merge of the LNAS and HNAS data. This is necessary because, although the IngestedFiles contained in the backup are preserved, the associated metadata is lost because it does not form part of the NDMP backup. The result is that, although the user data of migrated files and the directory structure that contained them will recover intact, the connection of this directory structure to the LNAS is not easily remade.

The sequence to recover, if NDMP replications or backups are used, is as follows:

  1. Prevent client access.
  2. Delete the association (if it has not been lost in the file system damage).
  3. Recover HNAS data to a location other than that which will be used for the association.
  4. If necessary, recover LNAS data.
  5. Recreate the association and allow virtualization to complete.
  6. There are now two sets of files, those recovered from the LNAS and virtualized, and those that were previously migrated and have been recovered to a separate location. Depending on the volume/type of files that are in the latter set , and how many renames/moves have happened, you can do either of the following:
    1. Examine the files manually and copy the migrated files into the virtualized directory structure, file by file, depending on some case-specific judgment.
    2. Use an automated method (rsync/robocopy) to move the migrated files into the virtualized directory structure.
  7. Allow client access.