Mark,

As with any performance question, the answer it "It depends"!  Before you
can decide whether or not you can put the 11th drive on the channel, you
have to see how much demand the other devices put on the channel.  If you
look at the sustained disk I/O rate on any given disk drive, you are
probably sustaining only 1-5 I/O's per second (that's common but, YMMV).
Adding it all up would indicate a maximum sustained disk I/O rate on
the channel of only 50 I/O's per second.  However, this is only the
high average sustained I/O rate.  You need to look at burst activity.
If your burst activity is significantly higher, you may run into periodic
disk I/O problems.  This will most likely occur during a transaction
manager checkpoint post to disk.

You may very will be able to live with the results.  Remember, that HP's
performance recommendations are always inherently conservative.  The
channel can handle approximately 150 I/O's per second.

Chances are you will probably be ok with 11 but, "It depends"!


Bill Lancaster


>We're considering adding additional disk drives to our 969KS200.
Presently we
>have 3 HASS enclosures containing 10 F/W SCSI 2GB disks on one channel
mirrored
>with 10 F/W SCSI 2GB disks on another channel.
>
>4 HASS slots remain.  I'm tempted to buy 2 x 4GB disks which will fill the
>remaining HASS slots, but that will result in 11 devices on each mirrored
>F/W SCSI channel.  The F/W SCSI maximum is 15 devices, but only 10 are
>recommended.
>
>Is anybody out there running with more than 10 F/W SCSI disks on a single
>channel?  Does your HP CE support that configuration?
>--
>Mark Bixby                      E-mail: [log in to unmask]
>Coast Community College Dist.   Web: http://www.cccd.edu/~markb/
>District Information Services   1370 Adams Ave, Costa Mesa, CA, USA
92626-5429
>Technical Support               +1 714 438-4647
>"You can tune a file system, but you can't tune a fish." - tunefs(1M)
>
>