David brings up a good point about multiple drives in the array.

To my mind, I am uncertain about the benefits of having multiple drives
declared in the array versus declaring a single big device or at least
as many as there are controllers.  I definitely see the benefits in
having multiple volume sets, but perhaps not many more devices beyond
that, except to get by the MPE limitations on drive sizes.

Denys

-----Original Message-----
From: HP-3000 Systems Discussion [mailto:[log in to unmask]]On
Behalf Of David N Lukenbill
Sent: Tuesday, February 17, 2004 9:24 AM
To: [log in to unmask]
Subject: Re: [HP3000-L] VA7110 LUN usage

I'm fairly impressed with the array.  I'm still setting up 3rd party
software on our system so it's difficult to really exercise the array,
but
it seems to be performing really well so far.  The Command View SDM
software is fairly nice.  It can be a little difficult at times, but
hasn't
been a major problem.

There is a bit of a conceptual difference in configuration.  It's a bit
different to think about the relationship between LDEV and drive usage
within the array.  (I wasn't sure how to best configure the LDEV to LUN
relationship since the array is using multiple drives for each LUN.  I
wasn't sure how much sense it made to configure multiple LDEVs when
using
the array.)

From an actual installation point of view, configuring the LUNs through
Command View, and setting up the array within MPE was pretty straight
forward.  I actually found the configuration to be similar enough to
SCSI
device configuration that it wasn't confusing.  (Well, once we figured
out
the correct boot path for the array.)

I wish the documentation for Command View was more complete.  The manual
describes what to find on each screen, but doesn't really discuss them.
I'd been pulling my hair out trying to figure out why the array and MPE
didn't agree on disk usage numbers.  I think Denys provided a pretty
reasonable theory ealier in this thread.  It would have been helpful to
have something in the manual explaining what the "capacity" information
within Command View represented.  I think it's natural to think of it as
"%
used" without something in the manual indicating otherwise.

David N. Lukenbill




====================
Denys Beauchemin wrote:

The VA7xxx series is a product of HP StorageWorks, a portion of Compaq
that HP acquired during the merger.  It has produced some very nice
products for quite a while now.  The mass storage stuff is really
excellent.  I am at a loss to say the same about their tape libraries.

I am actually quite impressed that HP was able to provide MPE support
for this mass storage equipment, even though it was done after the EOL
announcement for the HP 3000.  The biggest problem MPE users have with
this equipment is a version problem.  There has to be some patches
installed on 6.0 or 6.5 to make this device work.  Once you have that,
it is pretty straightforward.  But the other problem on MPE, is a lack
of understanding what such an array can do.  MPE people are more used to
a one-to-one relationship between device and Ldev or volume.  With the
virtual array, this relationship disappears, everything is, well,
virtual.  LUNs are also foreign to the MPE universe, but once these
concepts are understood, everything falls into place.

Perhaps this should be a thread on this list, or better yet, a session
at the Symposium or HP World.  After all, these storage devices are
going to be critical for homesteaders.

Denys

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