Nick Silkey wrote:
> 
> NDMP to TSM at $work is serially streamed for reasons I hear are TSM
> limitations. To reduce the backup window, we split data (VMware
> datastores) across several smaller flexvols as opposed to one flexvol
> to rule them all. IANABA, but it has to do with being able to
> concurrently go after drives in the library fo writes or something
> like that.

Getting off the original topic, but...  I run my LAN-free NDMP backups
to TSM semi-serially; I back up the volumes in each aggregate serially,
but concurrently across aggregates.  In my case, I've found the backups
to run faster serially within an aggregate than in parallel, where the
source streams are in contention for the same spindles.

I currently only back up volumes from two aggregates, so two concurrent
streams tying up two tape drives is acceptable.  If I had to back up a
lot more aggregates, I'd have to serialize backups of sets of aggregates
or buy more tape drives (or some combo).  TSM traditionally needs fewer
tape drives than other enterprise backup solutions for the same workload
(though this may be less true these days).  But it does a lot of other
data movement at times (storage pool backups, disk-to-tape migration,
tape reclamation, etc.) and things work better with some drives free for
that processing.

(There's other issues with NDMP to TSM -- and with NDMP in general --
but that's a topic for another list...)

-- 
Hello World.                                    David Bronder - Systems Admin
Segmentation Fault                                     ITS-SPA, Univ. of Iowa
Core dumped, disk trashed, quota filled, soda warm.   [email protected]
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