Chapter 6 HPSS ConfigurationHPSS Installation Guide September 2002 281Release 4.5, Revision 2Before deleting a basic migration policy, make sure that it is not referenced in any storageclass configurations. If a storage class configuration references a migration policy which doesnot exist, the Migration/Purge and Bitfile Servers will not start.When a migration policy is added to or removed from a storage class configuration, theMigration/Purge Servers must be restarted in order for migration to begin or end on this storage class. It isnot possible for Migration/Purge Servers to reread a migration policy for a storage class if the migrationpolicy was not assigned to the storage class when the Migration/Purge Server was started. Likewise, if amigration policy is removed from a storage class configuration, rereading the migration policy for this storageclass will not cause the Migration/Purge Server to stop migrating this storage class. It is necessary to recyclethe Migration/Purge Servers when a storage subsystem specific migration policy is added or removed. It isalso necessary to recycle when a storage class configuration is changed to use a different migration policy.Before changes made to a migration policy take effect, the Migration/Purge Servers must be either restartedor instructed to reread the policy from the MPS Storage Class Information window. If the Migration/Purge Servers are restarted, the changes to the migration policy are applied to all storage classes whichreference the policy. If the policy is reread, the changes are only applied to the storage class and storagesubsystem for which the policy is reread. It is not necessary to recycle Bitfile Servers when the parameters ina migration policy are changed.When a migration policy is added to or removed from a storage class configuration, the Bitfile Servers mustbe restarted in order for this change to take effect. If the Bitfile Servers are not restarted after a migrationpolicy has been added to a storage class configuration, migration records will not be created for files writteninto the storage class. These files will never be able to migrate even after the Bitfile Servers are restarted. Ifthe Bitfile Servers are not restarted after a migration policy has been removed from a storage classconfiguration, migration records will continue to be created for files written into this storage class. Thesemigration records will become orphaned metadata since migration is no longer supported on this storageclass. It is also necessary to restart the Bitfile Servers if a storage class configuration is changed to use adifferent migration policy. It is not necessary to restart the Bitfile Servers if a storage subsystem specificmigration policy is added or removed.Refer to the window's help file for more information on the individual fields and buttons as well asthe supported operations available from the window.
