Improve tape restores

We notice that when an VM Incremental Forever backup is to be restored (or mounted) a lot repeated tape mounts are performed and it takes a long time.

For instance, if in one of the tapes there is several chunks of data from different backup dates, Spectrum Protect gets those chunks sequentially and this means it may end up mounting that tape several times. The way I see, IBM should come with a solution to speed up data retrieval by allowing the user to setup an existing diskpool (or container) to act as a sort of buffer collecting all data chunks of a tape at once.


As stated by Tyler Shumway on PMR 91898,250,631

"If the data is stored on tape, then please use the VMSTORAGETYPE=TAPE option. I do not expect it to mount tapes more sequentially since it is only asking for the data chunks in ordrer. Where those chunks are stored on the tape volumes is not considered."

So, an example:

1) Current tape mounting to satisfy a VM IFINCR restore:

tape A has 3 chunks
tape B has 2 chunks
tape C has 4 chunks

mount tape A get chunk 1/3
mount tape B get chun 1/2
mount tape A het chunk 2/3
mount tape C get chunk 1/4
mount tape B get chunk 2/2
mount tape C get chunk 2/4
...

2) Using a buffered diskpool (DKP):

mount tape A get all 3 chunks and store them on the DKP
mount tape B get all 2 chunks and store them on the DKP
mount tape C get all 4 chiunks and store them on the DKP
serve the datamover with the restore data stream.

Thanks