/* define is_migrated uses GPFS inode attributes that mark a file as a migrated file. Use the define to include or exclude migrated files from the policy scan result explicitly */ define( is_migrated, MISC_ATTRIBUTES LIKE '%V%') RULE 'SYSTEM_POOL_PLACEMENT_RULE' SET POOL 'system' RULE EXTERNAL POOL 'Archive_files' EXEC '/opt/ibm/ltfsee/bin/ltfsee' OPTS -p 'pool1' SIZE(20971520) RULE 'ARCHIVE_FILES' MIGRATE FROM POOL 'system' THRESHOLD(80,50) TO POOL 'Archive_files' WHERE PATH_NAME LIKE '/ibm/glues/archive/%' AND NOT (exclude_list) AND (NOT (user_exclude_list) OR (user_include_list)) AND (is_migrated OR is_premigrated) 

To ensure that a specified IBM Spectrum Scale is migrated only once, run the mmapplypolicy command with the - -single-instance option. If this is not done, IBM Spectrum Archive EE attempts to start another migration process every two minutes. It is called every two minutes because the threshold continues to be exceeded while migrations are still in the process of migrating the data to free up the space. 

As a preferred practice, the user should not use overlapping IBM Spectrum Scale policy rules within different IBM Spectrum Scale policy files that select the same files for migration to different tape cartridge pools. If a file is already migrated, later migration attempts fail, which is the standard HSM behavior. However, this is not normally done, due to incorporating thresholds. 

Important:  If a single IBM Spectrum Scale file system is used and the metadata directory is stored in the same file system that is space-managed with IBM Spectrum Archive EE, migration of the metadata directory must be prevented. The name of metadata directory is /ibm/gpfs/.ltfsee/meta/ . 

By combining the attributes of THRESHOLD  and WEIGHT  in IBM Spectrum Scale policies, you can have a great deal of control over the migration process. When an IBM Spectrum Scale policy is applied, each candidate file is assigned a weight (based on the WEIGHT  attribute). All candidate files are sorted by weight and the highest weight files are chosen to MIGRATE  until the low occupancy percentage (based on the THRESHOLD  attribute) is achieved, or there are no more candidate files. 

Example 7-60 on page 165 shows a policy that starts migration of all files when the file system pool named “system” reaches 80% full (see the THRESHOLD  attribute), and continues migration until the pool is reduced to 60% full or less by using a weight that is based on the date and time that the file was last accessed (refer to the ACCESS_TIME  attribute). The file system usage is checked every two minutes. 

