=> On Sat, 12 Apr 2003 13:34:58 +1000, Paul Ripke <stixpjr AT BIGPOND.NET DOT 
AU> said:

> My gut feel (and the advice from an IBM TSM support guru here in
> Australia) is to have 3 or 4 volumes per spindle for database disks.
> Those "spindles" may be logical RAID5 arrays as in a shark, etc.

I guess we need terms of art here to be clear.  In my neck of the woods, when
we say 'spindle', it is to distinguish one set of platters inside one disk
from another.  Really, really, I mean "spindle".

If it's a RAID construct, then it's not a spindle, it's a volume or something.

And if it's a volume on a shark, then all bets are off: you're writing to
remote core.


> The reason, is to allow 3 or 4 outstanding requests to each disk, which the
> disk can then re-order to minimise over-all seek times. Since the TSM DB is
> primarily hit with random read I/O, this *should* be a win.

Which is precisely why, if you are arranging one TSM volume per spindle, you
don't want two or more competing queues of operations, be they read or write.


- Allen S. Rout