Troubleshooting
Problem
When data is needed to be migrated to another storage pool, how can automatic reclamation be voided?
Symptom
When migrating data to a new storage pool, or next storage pool, it can be seen that reclamation occurs within the source storage pool, and no migration occurs.
Cause
This behaviour is normal for migration process.
Space reclamation is expected to be more efficient than storage pool migration. For example, if a 500GB capacity scratch volume contains 2GB of data, representing one segment of a 50GB file, reclamation can return 500GB of storage space to the pool by moving 2GB of data and returning the volume to scratch. To achieve the same result, migration would need to move 50GB of data.
If reclamation brings the storage pool below the migration threshold, the server can avoid performing any storage pool migration.
The space reclamation performed by a migration process behaves as a normal space reclamation operation. For example, volumes are chosen based upon the reclamation threshold of the pool in which they reside.
Resolving The Problem
This behaviour can be avoided by either:
Using "move data" instead of "migration"
or
By setting the maxscratch to 0 and setting the storage pool to read only for the source pool using "update stgpool" command, that should prevent reclamation from being able to do any reclamation processing in the source storage pool.
Related Information
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Document Information
Modified date:
17 June 2018
UID
swg22014323