Migration Policies

You can set the values in the Migration resource that HSM uses to determine what the client filesystem capacity should be for migration to start and stop. From the nwadmin GUI, select Migration Setup from the Clients menu. For each migration client, you determine the following:

• High water mark - specifies the percentage of disk space filled. When this value is reached, migration starts automatically.

• Low water mark - specifies the percentage of disk space filled after migration. When this value is reached, migration stops.

When the client filesystem reaches the specified high water mark, the Backup HSM application automatically migrates the files that meet the defined criteria.

In addition to the high and low water marks, you must set one or more criteria that files must meet to become candidates for migration. If you set more that one criteria, files must meet all the specified criteria to become candidates for migration. For example, you can set a policy that specifies when the client filesystem exceeds 70% full, files in the /home directory that have not been accessed in over 60 days and are at least 2 KB or larger in size are automatically migrated. You can set the following migration criteria:

• Last access time - specifies the length of time since a file was last accessed.

• Minimum file size - specifies the minimum file size to consider for migration. Files smaller than this entry do not provide enough available disk space after being replaced with a stub file to warrant migrating them.

• File owner - specifies the name of the owner of the file you want considered for migration. If you want all owners allowed, leave this text box blank. If you want all owners allowed except for owner_name, enter -owner_name in the field.

• File group - specifies the name of the group with access to the files to be migrated. If you want all groups allowed except for group_name, enter -group_name in this field.

• Preserve - specifies the files you do not want migrated. These entries must be full pathnames and may contain UNIX shell wildcard characters.