IBM TSM - How to reclaim offsite tapes for reuse


If you have many offsite tapes particularly in relation to how much data your are backing up then the offsite tapes may be under utilised.

First check the utilisation of the volumes in your offsite copy storage pools by running the following SQL query.

select a.stgpool_name,a.volume_name,a.pct_utilized,a.pct_reclaim from volumes a,stgpools b where a.stgpool_name=b.stgpool_name and b.pooltype='COPY' order by a.stgpool_name,a.pct_utilized

You should get output similar to the following.

------------------     ------------------     ------------     -----------
OFFSITE             	VOL049L2                        0.9            99.1
OFFSITE             	VOL097L2                        1.9            98.0
OFFSITE             	VOL011L2                        2.0            97.9
OFFSITE             	VOL083L2                        2.0            98.0
OFFSITE             	VOL031L2                        2.2            97.7
OFFSITE             	VOL067L2                        2.5            97.7
OFFSITE             	VOL038L2                        2.6            97.3
OFFSITE             	VOL046L2                        3.7            96.2
OFFSITE             	VOL045L2                        4.8            95.7
OFFSITE             	VOL077L2                        5.2            95.0
OFFSITE             	VOL058L2                        8.5            92.1
OFFSITE             	VOL040L2                        8.7            91.2
OFFSITE             	VOL030L2                        9.5            90.9
OFFSITE             	VOL041L2                       17.6            82.4
OFFSITE             	VOL035L2                       27.1            73.8
OFFSITE             	VOL091L2                       31.1            69.1
OFFSITE             	VOL080L2                       38.6            61.3
OFFSITE             	VOL095L2                       51.9            48.4
OFFSITE             	VOL044L2                       52.5            47.6
OFFSITE             	VOL016L2                       54.1            47.0
OFFSITE             	VOL022L2                       86.2            13.8
ORA_OFFSITE        	VOL078L2                       38.8            61.1
ORA_OFFSITE        	VOL076L2                       40.7            59.2
ORA_OFFSITE        	VOL033L2                       50.5            49.4
ORA_OFFSITE        	VOL034L2                       51.9            48.0
ORA_OFFSITE        	VOL053L2                       68.3            31.6
ORA_OFFSITE        	VOL002L2                       71.7            28.2
ORA_OFFSITE        	VOL061L2                        0.0             0.0
ORA_OFFSITE        	VOL073L2                       46.2             0.0
ORA_OFFSITE        	VOL096L2                       52.6            47.3
ORA_OFFSITE         	VOL081L2                        0.0             0.0
ORA_OFFSITE         	VOL001L2                        5.7            94.2
ORA_OFFSITE         	VOL029L2                       59.4            40.5
ORA_OFFSITE         	VOL006L2                       91.3             8.6

As you can see there are quite a few tapes under 10% utilised.

Next check the reclamation threshold for your offsite copy pool. To do so type the following.

q stg OFFSITE f=d

Substitute OFFSITE with the name of your offsite storage pool.

You should get output similar to the following.

	       Storage Pool Name: OFFSITE
               Storage Pool Type: Copy
               Device Class Name: LTOCLASS
              Estimated Capacity: 395,489 G
              Space Trigger Util:
                        Pct Util: 0.4
                        Pct Migr:
                     Pct Logical: 98.7
                    High Mig Pct:
                     Low Mig Pct:
                 Migration Delay:
              Migration Continue:
             Migration Processes:
           Reclamation Processes: 1
               Next Storage Pool:
            Reclaim Storage Pool:
          Maximum Size Threshold:
                          Access: Read/Write
                     Description: Storage pool 
               Overflow Location:
           Cache Migrated Files?:
                      Collocate?: No
           Reclamation Threshold: 50
       Offsite Reclamation Limit: No Limit
 Maximum Scratch Volumes Allowed: 999
  Number of Scratch Volumes Used: 21
   Delay Period for Volume Reuse: 0 Day(s)
          Migration in Progress?:
            Amount Migrated (MB):
Elapsed Migration Time (seconds):
        Reclamation in Progress?: Yes
  Last Update by (administrator): admin
           Last Update Date/Time: 07/17/2009 11:30:21
        Storage Pool Data Format: Native
            Copy Storage Pool(s):
         Continue Copy on Error?:
                        CRC Data: No
                Reclamation Type: Threshold

Note that the Reclamation Threshold is set to 50%. If it is set to 100% then reclamation is switched off.

With a reclamation threshold of 50% any tapes with 50% or less utilisation should get reclaimed. Therefore our tapes under 10% utilised should have been reclaimed. If they don't it maybe that the reclamation process doesn't get time to reclaim them, always trying to reclaim the more heavily utilsed tapes first.

A quick way of reclaiming these tapes is to increase the reclamation threshold of the storage pool to 90%.

To set the threshold to 90% for this storage pool type the following.

upd stg OFFSITE reclaim=90

Substitute OFFSITE with the name of your offsite storage pool.

The next time reclamation runs it will reclaim any tapes that have a utilisation of 10% or below.

These will be available to check in to the onsite library as scratch.

However you may want to set the threshold lower than 90% for the long term.