The number of users and/or jobs is a consideration.  If you have lots of
users, all sharing the same system disk for transient space, performance can
suffer.  I've seen it happen.  If you have a small number of users, a single
system disk may not be so bad.  Exactly where the threshold is...who knows?
I guess it depends on many other factors.

We recently set up a 969/120 using Mirror/iX for our non-system volume set,
and used a Nike 20 array for our MPEXL_SYSTEM_VOLUME_SET (yes, I cut and
pasted the name).  Our Nike has six disks; the first two are mirrored as
LDEV 1, the next three are RAID5 as LDEV 2, and the sixth is a hot spare.
We have about 60-70 users on that system and it seems to be performing just
fine.

Best of luck,
Tim Busche

-----Original Message-----
From: Ward Hammond [mailto:[log in to unmask]]
Sent: Wednesday, November 18, 1998 3:42 PM
To: [log in to unmask]
Subject: MPEXL_SYSTEM_VOLUME_SET


It's not so much the number of spindles as the amount of space.  LDev 1
needs at least 4 GB as a boot device to insure all system required
functions work properly.  4 GB is also the maximum a non-internal boot
drive will use (coincidence?).  It is recommended that you have 3 spindles
on the system volume to handle the performance load of spooling and system
command calls.  I have setup systems with 1 or 2 spindles but only when I
was sure the spooling activity would be very low and/or the client was
aware of the potential problem.
---------------------- Forwarded by Ward Hammond/Forsythe on 11/18/98 03:29
PM ---------------------------


[log in to unmask] on 11/18/98 12:56:42 PM

Please respond to [log in to unmask]

To:   [log in to unmask]
cc:    (bcc: Ward Hammond/Forsythe)
Subject:  MPEXL_SYSTEM_VOLUME_SET




I am setting up a new 969KS120 with mirroring.
I have all drives but Ldev1 set up as a private volume, mirrored.
There is only one drive, Ldev1 in the system volume. HP tells me that this
is a valid configuration.

However, the response centre now tells me that I may (or may not) see
performance problems since I only have the one spindle in the system
volume.

As far as I can see I will have spool files and transient files going to
the system volume. Everything else is on the private volume.

Anyone have any experience with this?

Keith Porter
System Manager
Hamilton Discount Corp.