CTA Orphan Delete and Garbage collection in Centera

~ From CTA, if we run Orphan file deletes, will it reclaim the space back to the Centera pool ?

Orphan Delete issues a command to secondary storage (Centera), telling it to delete the files (C-Clips).  The Centera returns an acknowledgement when the task is executed, but only marks the C-Clip for deletion.  The object space is not immediately returned to the Centera pool.

~ or even after running the orphan file delete, a Garbage collection in Centera needs to be ran inorder to reclaim the space back to the pool ?

Correct.  The GC sweep will recover the fragments of the deleted C-Clip and return the space to the Centera pool.

~ Does both CTA orphan file Delete and Garbage collection in Centera does exactly the same job or what is the difference between them ?

Both jobs do something very different.  Garbage collection on the Centera looks for expired objects, and reclaims their fragments.  Orphan deletion marks objects for deletion by the Garbage collection process. Both jobs are, in fact, necessary.

~ Once the C-clips are deleted by the application, is there any retention period set, so that when it expires, then only the GC process will delete the blobs and reclaim the space back to the centera pool ?

After CentraStar 3.1, support was added for compliance at the pool level.  Before a default retention for the entire Centera cluster was implemented.  Now, this retention can be configured on a per-pool basis.  That is, Pool A can have a default retention of 1yr, meaning, no C-Clips will be deleted until they are over 366 days old, while Pool B can have a retention of 1 day.  Note that changing retention on a pool only affects new objects being written - all old objects keep their original retention.

You must check the pool configuration for each pool, to see if the Enforce Retention flag is set to Yes.

Let us know if that helps!

Karl

Hi all

The pool default retention is only used when the application does not set anything. If CTA set's the retention this one will be used. If the default is 1 year and CTA set it to 0 this will be used unless the advanced retention management features are enabled and configured on the pool. This would be the enforce retention flag then as mentioned above but bear in mind that this is not available without the ARM license.

In any case, the application will have to issue the delete for an object for the Centera to delete the content. This after the retention has expired.

Best regards, Holger