When marking a tape as free it is removed from the catalog to be used again. But seems that it is better to move it to the Free pool.
@Chris.Childerhose Same operation basically. Both will start a Remove from Catalog operation where we clean up the tape catalog entries on the DB, so in effect there’s no difference. (Hint: you can re-catalog a tape that was marked as free/moved to free BEFORE it is written to again, and you will re-import the backups on that tape)
@dloseke is correct here, deleting entries from an SQL database does not decrease the size of the database. It’s best to think of a database as a container for your SQL data; as more space is needed, the container allocates more pages which result in more physical disk space being used. It’s easy to allocate new space, but shrinking requires a lot of work because SQL organizes the data in an optimized way -- just deleting data requires a lot of planning from the SQL engine to ensure it doesn’t make performance worse, and it’s usually a dedicated operation. Similarly, this will result in indices being rebuilt which can be very expensive CPU wise (read: CPU spikes, performance issues)
So you can “reclaim” space in that individual pages that aren’t needed anymore are deleted from the container, but the container remains the same size, just it now has more free space than it did before.
@Nikks, is it just VM/Agent backups or are you also doing Unstructured Data (File/Object) to tape? I would not expect huge space savings with VM/Agent backup to tape, but File/Object to tape is very expensive space wise in the DB so I can get why you want to reclaim space, but this can be a tricky operation. I would honestly suggest schedule a maintenance window after you have done a substantial amount of tape “mark as free”, and during the maintenance window, take a fresh configuration backup, then restore the configuration backup to a NEW database on the same server. Test it and make sure all looks good and works, and if so, you can delete the original database. This would basically rebuild the configuration database anew and effectively shrink it as only necessary space will be allocated.
