The guideline I received from HP and EMC about a year ago is to not have
more than about 48 GB of space assigned to a particular controller if
performance is your goal.  If performance is not as critical then add more
disk to the channel until it hurts!  With the newer, faster drives that are
now out I'm not sure how the 48 GB recommendation gets changed.

You will want to spread the data among the physical EMC disks to avoid
potential bottlenecks.  Because of EMC's numbering scheme this is not hard
to do if you just assign things sequencially.

Just to see how far I could take the Symm box/MPE, I once assigned all the
logical disks, five 4GB partitions to be exact, from a single physical EMC
disk to a single MPE volume set.  Each disk was on its own scsi channel so
througput to the box was at a maximum.  I then started writing data to the
volume set from a couple of batch jobs.  Did you know that MPE will crash if
you fill up the I/O Requests table that keeps track of all the pending
I/O's?  It will!  Ah, another learning experience. :)

Anyway, the moral to this story is that you should spread the volume sets
over physical disks.  In our environment we found that 2-3 logical
partitions from a physical disk was all we could assign to a volume set
without impacting performance.

Hope this helps!

Carl McNamee
Systems Administrator
Billing Concepts
(210) 949-7282

-----Original Message-----
From: Thomas M. Root [mailto:[log in to unmask]]
Sent: Wednesday, August 08, 2001 2:38 PM
To: [log in to unmask]
Subject: [HP3000-L] Configuration suggestions for a Summetrix storage
array


Desert Schools Credit Union is about to install an EMC Summetrix storage
system and I would like to get some configuration recommendations from those
of you who have been down this path.

Summit, our software provider, recommends spreading our databases over many
disk drives to maximize the potential for I/O concurrency.  Even though the
logical disks configured on the 3000 don't directly correspond to spindles
on the Summetrix, I speculate that this is still good practice so that the
3000 can maximize the number of requests passed to the storage array.  Is
this correct?

As I understand it, each FWD SCSI controller can be configured with up to 15
target IDs and each ID may be configured with up to 16 logical devices.  Is
it better to use a few SCSI IDs with lots of logical devices, or use lots of
IDs with fewer devices?

Any other insights would be greatly appreciated.

Thomas M. Root <[log in to unmask]>
Desert Schools Federal Credit Union
Phoenix, AZ

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