BlueArc Data Migrator
System Administration Manual
219
Reclaimed space
Reclaimed space is the difference in space between the start of the migration and when the
migration completed. It is not a report of the mount of data migrated from the source file system
to the target. For this detail, refer to Amount Migrated.
It is likely that the file system will be in use by network clients while the migration is in
progress. As a result, the reclaimed space can be substantially different than the amount
migrated. The value can even be negative if files were added to the source.
Once a data migration has completed, copies of the files may be preserved on the source file
system in snapshots. For the space to be fully reclaimed, all snapshots on the source file system
that reference the migrated files must be deleted.
Reverse Migration
Though Titan does not support automatic reverse migration of files, it is possible to restore a
migrated file in two different ways:
Reverse Migration through the Titan CLI
Individual files or whole directory trees can be reverse-migrated through the CLI. The files which
are included in the reverse migration can be identified by pattern or by last access time. For
detailed information on this process, run man
reverse-migrate
at the CLI.
Reverse Migration from a network client
A file can be restored from a network client by performing the following sequence of operations:
1.
From a Windows or Unix client, make a copy of the file (using a temporary file name) on
the Primary Storage. This copy of the file will reside fully on Primary Storage.
2.
Delete the original file. This will delete the link on Primary Storage, and the migrated
data from Secondary Storage.
3.
Rename the copied file to its original name.
Considerations when using Data Migrator
Titan uses Data Migrator with the following considerations:
Snapshots
To preserve snapshot protection on migrated files, when snapshots are created on the primary
file system, corresponding snapshots are automatically created on the secondary file system.
Likewise, when a snapshot is deleted on the primary file system, the corresponding snapshot on
the secondary file system will also be automatically deleted.