based on individual files rather than tape volumes, and is able to make second copies of files
stored on tape. In this algorithm, individual files are selected for migration based on their last
write time and the settings in the Migration Policy. The selected files ar e migrated downwards to
the next level in the hierarchy. The order in which files are migrated is based approximately on
the order in which they are written to tape. Prior to migration, however, the files are sorted by
source tape volume, so their migration order may vary. In this algorithm, files at the source level
are never purged. Note that the source tape storage class must be repacked and reclaimed
manually.
Migrate Files and Purge. The tape files will be moved to the next lower l evel in the hierarchy.
No duplicate copy is maintained.
This enables the same file-based tape migration algorithm as Migrate Files, but purges fil es
from the source level when they are successfully migrated. Additionally, this algorithm considers
both the read and write times for a candidate file against the settings in the Migration Policy.
This algorithm is useful for moving inactive files to a lower hierarchy level. Note that the source
tape storage class must be repacked and reclaimed manually. Also note that if migrated files are
staged up in the hierarchy, HPSS does not run a purge policy to delete the cached copy at the
higher level.
Related Informatio n
Section 4.2.3.7: Migration and Purge Policy Overrides on page 81.
6.4.2.3. Changing a Migration Policy
To update an existing basic migration policy, select the policy from the Migration Poli cies list window
and press the Configure button. The Disk or Tape Migration Policy window will appear. Make the
desired changes to the basic policy and sub-system policies by selecting the appropriate tabs and placing
new values in fields. When all changes have been made, press the Update button to record the changes .
Before changes made to a migration policy take effect, the Migration Purge Servers must be either
restarted or instructed to reread the policy via the MPS Storage Class I nformation window. If the
Migration Purge Servers are restarted, the changes to the migration policy are applied t o all storage
classes that reference the policy. If the policy is reread, the changes are only applied to the storage class
and storage subsystem for which the policy is reread. It is not necessary to recycle Core Servers when the
parameters in a migration policy are changed.
6.4.2.4. Deleting a Migratio n Policy
Before deleting a basic migration policy, make sure that it is not referenc ed in any storage class
configuration. If a storage class configuration references a migration policy that does not exist,
the Migration Purge and Core Servers will not start. Be sure to check the Migr Policy column of
the Configured Storage Classes list for any storage class that reference s the Migration Policy to
be deleted.
Be sure to recycle Core Servers and Migration Purge Servers after deleti ng a Migration Policy.
Simply reinitializing them to reload the configuration is not suffi cient.
HPSS Management Guide November 2009
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