RE: More disk arms myth exploded...

[rob@xxxxxxxxx]

I know, they kept that new controller pretty much under wraps and it 
hasn't settled well with the boss.  Discussions are in place.

This is the point I want to attack.  "That cutting back to 16% the number 
of arms may hurt performance."  You just can't argue with the numbers. I'd 
bet that the new drives/controllers would still outperform the old ones, 
even with both loaded to 90%.  I know, it requires that you believe that 
technology can actually advance to the point that a modern 
drive/controller can be that much of a better performer than the older 
ones. Granted, I agree that you have to have at least enough drives to 
make a decent raid set.  But maybe that's one point that I'm not ready to 
change on my part.  :-)

Rob Berendt
-- 
Group Dekko Services, LLC
Dept 01.073
PO Box 2000
Dock 108
6928N 400E
Kendallville, IN 46755
http://www.dekko.com





Glenn Ericson <Glenn-Ericson@xxxxxxx> 
Sent by: midrange-l-bounces+rob=dekko.com@xxxxxxxxxxxx
08/13/2004 01:58 PM
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Subject
RE: More disk arms myth exploded...






John  the H23 is the HDV  model. Try the L23 and the LDV controllers- 
it  can   near match the speeds of  fiber . For  DASD  controllers  try 
the  new 2780  controller over the  2757  with 1GB  read cache and757MB 
write cache.  Another item was  a mix of several different DASD sizes and 
rpm rates, which is not  a performance plus.

Frankly,  in a production system, I'd be challenged to cut back to 16% of 
the  original arms and expect continued performance 
as  those  bigger  drives begin to fill  with  data  or trash.


>-----Original Message-----
>date: Fri, 13 Aug 2004 10:49:01 -0500
>from: "Jones, John (US)" <John.Jones@xxxxxxxxxxxxxxxxxxxxxxx>
>subject: RE: More disk arms myth exploded...
>
>
>I would guess #1: Tape controller.  On our 730 using 3580-H23 drives,
>saves at 70GB/hour over a 6534.  On our 830 using the same drive types
>but a 2729, we get 200GB/hour.  The machines have similar RAM, CPW, #
>disk arms, etc.  And really, more than the tape controller it's the SPD
>bus.
>
>You could also potentially mention the spreading of the data will be
>optimal on the 520 as it was a reload. But I don't think it would make
>that large of a difference.
>
>John A. Jones
>Americas Security Officer
>Jones Lang LaSalle, Inc.
>V: +1-630-455-2787 F: +1-312-601-1782
>John.Jones@xxxxxxxxxxxxxxxxxxxxxxx
>
>-----Original Original Message-----
>From: rob@xxxxxxxxx [mailto:rob@xxxxxxxxx]
>Sent: Friday, August 13, 2004 10:06 AM
>To: midrange-l@xxxxxxxxxxxx
>Subject: More disk arms myth exploded...
>
><snip>
>
>Don't know if it:
>1)      was the difference between the 6534 and the 2749 card
>2)      the way we have them configured (do we have the tape card on the
>
>520 not sharing a processor with disk and not the same on the 820?)
>3)      or the difference between the 520 and the 820
>
><snip>
>
>Rob Berendt
>--
>Group Dekko Services, LLC
>Dept 01.073
>PO Box 2000
>Dock 108
>6928N 400E
>Kendallville, IN 46755
>http://www.dekko.com
>
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