==> In article <B4FE6832-D13B-11D8-BD90-000502638BD0 AT stix.homeunix DOT net>, 
Paul Ripke <stix AT STIX.HOMEUNIX DOT NET> writes:


> With any disk and controller technology that supports command queuing (SCSI2
> command tagged queuing, SATA Native Command Queuing (NCQ)), you are better
> off with about 3 volumes per spindle for random I/O.  TSM serialises I/O per
> volume, meaning only one I/O in flight to each volume at any one time.

Hmm. This is the first I've heard about NCQ; any pointers to which devices and
which firmware levels do this?  I've got some rather old 9G SSA which might
not do the trick.

But I'll fiddle with it on my new 36Gs; if I can get acceptable performance
out of them this way, I'll be exstatic.


> This is backed up by tests I've run, and is recommended by one of the IBM
> TSM support guys here in Australia.


- Allen S. Rout