TSM uses a hierarchy of Storage Pools to “migrate” or move data from one type of storage to another or to the same type of storage.

How does Migration work?

There are a couple of parameters that need to be setup to facilitate migration. The first is to setup the “Next Storage Pool” parameter, this defines which pool the data will “migrate” to from the current pool.

To see how this is currently defined on your storage pools

Run the following Admin CLI Command

QUERY STGPOOL F=D and look at the “Next Storage Pool” field

In TSM Studio open the Storage Pools Dataview from the Storage category and check out the NextStgPool column

 To change the Next Storage Pool from the Admin CLI

 UPDATE STGPOOL stgpoolname NEXTSTGPOOL=nextstgpoolname

 From TSM Studio

Right Click on the Storage Pool and Choose Next Storage Pool and then choose the storage pool

The next part is setting the migration threshold parameters which tell TSM when to move the data from the current pool to the “Next Storage Pool”. These two parameters are

Low Migration and High Migration, they represent a percentage full threshold for the storage pool that they are defined on

These Parameters function like this

TSM writes data to the current pool, the current pool hits the High Migration Threshold and will start “migrating” data to the storage pool defined in the “Next Storage Pool” field.

TSM will keep “migrating” data until it reaches the Low Migration Threshold and will then stop and wait for the High Threshold to be hit again

To Change the Low Migration or High Migration from the Admin CLI

UPDATE STGPOOL stgpoolname LOWMIG=xx HIGHMIG=xx

From TSM Studio, Select the Storage Pool and right click and choose Migration Thresholds and then choose the values

Ideally you will want enough disk space in your Primary Disk pool to store the nightly backups and while the nightly backups are running you will keep the high migration value somewhere around the 80 mark and low migration value somewhere around the 60 mark just so you don’t run out of space in the Primary Disk Pool.  During this time you can be running other TSM admin tasks such as reclamation.

 In the morning when your backups have finished or close to finishing you can change the High Migration to 5 and Low Migration to 0, this will then force all the data from the Primary Disk Pool ( Usually to Tape ).

This is not the only way this can be done and you may have reasons to run things differently and if you have a VTL you may wish to run with low values continuously.

Another Parameter related to Migration is the Migration Processes parameter, this defines how many processes will be used to Migrate the Data to the Next Storage Pool. When moving from the Primary Disk data to a Primary Sequential Pool (In most cases this is usually a tape pool) each process will use one tape drive.

UPDATE STGPOOL stgpool MIGPROCESS=xx 

From TSM Studio, Select the Storage Pool, Right Click and choose Migration Processes.

These procedures can be automated using Administrative Schedules  

To stop Migration set  HighMig=100 and LowMig=99 and to Migrate everything HighMig=0 and LowMig=0

Posted in: TSM Studio