Enabling the object heatmap policy

Use this procedure to enable the object heatmap policy.

1. Run the following command to create a file that is named file_heat_policy and also add the following policy:

   RULE 'DefineTiers' GROUP POOL 'TIERS' 
   IS 'system' LIMIT(70) 
   THEN 'gold' LIMIT(75) 
   THEN 'silver' 
   RULE 'Rebalance' 
   MIGRATE FROM POOL 'TIERS' 
   TO POOL 'TIERS' WEIGHT(FILE_HEAT) 
   FOR FILESET('Object_Fileset')
   WHERE NAME LIKE '%.data'

   This policy places the most frequently accessed objects in the SSD-backed system pool until the system pool reaches 70% of its capacity usage. Frequently accessed objects are placed in the gold pool until it reaches 75% capacity usage.

   Note:

   The temporary files that are generated by Swift are not moved between storage tiers because they are all eventually replaced with permanent files that have the .data extension. Moving temporary files to system, gold, or silver storage pools results in unnecessary data movement.

2. To enable the object heatmap policy for unified file and object access, identify the filename prefix for temporary files that are created by Swift in unified file and object access. The file name prefix is configured in the object-server-sof.conf directory. Run the following command to fetch the file name prefix:

   grep tempfile_prefix /etc/swift/object-server-sof.conf 
   tempfile_prefix = .ibmtmp_

3. Run the following command to determine the filesets that are enabled for unified file and object access:

   mmobj policy list 
   Index   Name         Default Deprecated Fileset     Functions              
   ----------------------------------------------------------------------------------------
   0       SwiftDefault yes            obj_fset                                 
   1317160 Sof                         obj_Sof   file-and-object-access 

4. Run the following command to create a heat-based migration rule by creating the following file:

   
   RULE 'DefineTiers' GROUP POOL 'TIERS'                   
         IS 'system' LIMIT(70)
         THEN 'gold' LIMIT(75)
         THEN 'silver'
   RULE 'Rebalance' MIGRATE FROM POOL 'TIERS'                   
         TO POOL 'TIERS' WEIGHT(FILE_HEAT)
   FOR FILESET('obj_Sof')
   WHERE NAME NOT LIKE '.ibmtmp_%'

   Note:

   • The fileset name is derived from Step 3. Multiple fileset names can be separated by comma.
   • The filename prefix in the WHERE clause is derived from Step 2. By using this filter, the migration of temporary files is skipped - which avoids unnecessary data movement.
5. Run the following command to test the policy:

   mmapplypolicy fs1 -P object_heat_policy -I test
   [I] GPFS Current Data Pool Utilization in KB and %
   Pool_Name                 KB_Occupied             KB_Total    Percent_Occupied
   gold                        169462784           6836715520        2.478716330%
   silver                         136192          13673431040        0.000996034%
   system                        8990720          13673431040        0.065753211%
   [I] 6050 of 42706176 inodes used: 0.014167%.[I] Loaded policy rules from object_heat_policy.
   Evaluating policy rules with CURRENT_TIMESTAMP = 2015-11-22@02:30:19 UTC
   Parsed 2 policy rules.
   RULE 'DefineTiers' GROUP POOL 'TIERS' IS 'system' LIMIT(70)THEN 'gold' LIMIT(75)THEN 'silver'
   RULE 'Rebalance' MIGRATE FROM POOL 'TIERS' TO POOL 'TIERS' WEIGHT(computeFileHeat
   (CURRENT_TIMESTAMP-ACCESS_TIME,xattr('gpfs.FileHeat'), KB_ALLOCATED))FOR FILESET('Object_Fileset')
   WHERE NAME LIKE '%.data'
   [I] 2015-11-22@02:30:20.045 Directory entries scanned: 1945.
   [I] Directories scan: 1223 files, 594 directories, 128 other objects, 0 'skipped' files and/or errors.
   [I] 2015-11-22@02:30:20.050 Sorting 1945 file list records.
   [I] Inodes scan: 1223 files, 594 directories, 128 other objects, 0 'skipped'files and/or errors.
   [I] 2015-11-22@02:30:20.345 Policy evaluation. 1945 files scanned.
   [I] 2015-11-22@02:30:20.350 Sorting 1 candidate file list records.
   [I] 2015-11-22@02:30:20.437 Choosing candidate files. 1 records scanned.
   [I] Summary of Rule Applicability and File Choices:
    Rule#	    Hit_Cnt	     KB_Hit	     Chosen	  KB_Chosen	     KB_Ill	Rule
        0	   98080572	 3353660160	   39384107	 1328389120	     292416	RULE 'Clean' 
   MIGRATE FROM POOL 'TIERS' WEIGHT(.) TO POOL 'TIERS' FOR FILESET(.) WHERE(.)
   
   [I] Filesystem objects with no applicable rules: 1944.
   
   [I] GPFS Policy Decisions and File Choice Totals:
    Chose to migrate 0KB: 1 of 1 candidates;
   Predicted Data Pool Utilization in KB and %:
   Pool_Name                   KB_Occupied         KB_Total    Percent_Occupied
   gold                          169462784       6836715520        2.478716330%
   silver                           136192      13673431040        0.000996034%
   system                          8990720      13673431040        0.065753211%

6. Run the following command when you have no errors:

   mmapplypolicy fs1 -P object_file_heat -I yes