User's Manual

112 Migration, release, recall, and deletion
Migration
The relevant configuration parameters for the migration policy are specified in the FSE partition
configuration file. It is very important that you create a migration policy appropriate for your environment.
You should check the default migration policy and adjust settings according to the characteristics of your
files.
FSE migration policies are based on file age, wait time for migration, number of files waiting for migration,
and the migration volume. Applying these migration parameters in combination creates archival
(migration) and retrieval (recall) processes that make the most effective use of the underlying hardware and
network infrastructure.
NOTE: You can make redundant copies of the file data during the migration job. For more information,
see ”Multiple copying” on page 131.
What is a retried migration?
In case of a failed migration, where files would remain on the migration candidate list and would not be
migrated, the migration of such files can be triggered manually from the command line or configured to be
run periodically by a cron job (on Linux platform) or scheduled task (on Windows platform).
Use the following command to trigger migration:
Adding files to the dirty file list manually
Sometimes it can happen that a file is present on the HSM file system but is not recognized by FSE at a
given time. By putting it to the dirty file list the file is recognized and its attributes are preserved. Another
file could already be migrated to the FSE medium that has its current status set to unreliable, and is only
available for recall if no other copy exists. Such a file can be remigrated to another medium.
In such cases you should manually add files to the dirty file list as follows:
Once the files are added to the dirty file list, they are later moved to the migration candidates list and
migrated regularly, according to the migration policy. If the specified file is offline, it will be recalled and
then regularly migrated with other files on the list.
Note that zero-size files are always online; they cannot be migrated nor released.
Migration policy parameters
The configuration parameters for migration along with their definition and impact are listed below. The
combination of these parameters allows a flexible configuration of migration behavior.
Minimum file age for migration (MinFileAge)
Minimum wait time for migration (MinWaitTime)
fsefile --trigger-migration PartitionName
fsefile --migrate FileName
Definition A period of time after file creation/change during which a file must be left intact to
become a migration candidate.
Impact You should define the parameter value according to the characteristics of your file data;
if your parameter value is too high, for example 5 minutes, and the file is constantly
changing (e.g. it is updated every 2 minutes), the file will not be migrated to media.
Definition Minimum wait time for files on the migration candidate list during which no more files are
added to the list.
Impact If this parameter value is high, for example 8 hours, you will have irregular and
substantial migrations. A low value results in frequent, smaller migrations.