Carl,

The maximum number of LDEVs on a fast-wide controller is 15 (using target
mode addressing). The recommendation of 8-10 drives is one that I have heard
frequently and agree with. The "size" of the LUNs is the limiting factor. If
they LUNs were 11.5GB (2:1 splits for each physical), you would be able to
assign more "storage per interface". Of course, this means a LONG WEEKEND
reload :(

The caveat - I have been told by EMC engineers more than once that they
recommend not exceeding 45GB per controller on MPE. I do not necessarily
agree with this metric, as I have worked with customers running twice this
per FWD controller without a performance impact. The config that I refer to
was consiting of 18GB physical drives with 9GB LUNs.


Regards,

>       _________________________________________
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>       Rocky J. Costantino
>       Vice President
>
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-----Original Message-----
From: Carl McNamee [mailto:[log in to unmask]]
Sent: Friday, April 07, 2000 10:01 AM
Subject: EMC on HP3k question


This is a cross post from the EMC list server:

A bit of back ground and a summary of our problem. We have a 3700 frame that
is about 60% full of 23GB drives. The drives are split into 4.6GB logical
partitions. We assigned drives to the controllers based on HP's
recommendation of no more than 8-10 drives for performance since we have
some very i/o intensive applications.
My problem is that all 32 controllers all "full", e.g. have 8-10 drives
assigned, but the emc box is only half full of drives. What I am interested
in is how many drives you have assigned to each controller?
HP's theory on the 8-10 drives deals with an optimal number of spindles, if
I'm not mistaken. Since a logical emc drive does not necessarily equate to a
spindle we are thinking about stringing the drives out 15-20 per controller
so that we can fill the frame with drives. In our theory we would just need
to ensure that we did not exceed the capacity of the f/w scsi channel during
peak processing. I think that this can be done by arranging the drives so
that we have a good mix of low use drives and high use drives on each
controller.
Any thoughts or comments? Feel free to poke holes in this!
Carl McNamee
Systems Administrator
Billing Concepts