RE: AS/400 UPGRADE

["Richard Jackson" <richardjackson@xxxxxxxxxxxxxxxxxx>]

Chris:

I like this one:

[from the IBM web site http://www.as400.ibm.com/hsmcomp/storagenews.htm]

#2748 PCI RAID Disk Unit Controller is a higher performance PCI IOA, with a
faster onboard processor. It offers RAID-5 protection, and 26MB of fast
write cache. Optionally, it supports Integrated Hardware Compression or
Extended Adaptive Cache.

But you have to have stuff to support the PCI bus.  If you have the SPD bus,
then the 6533 is good.  Before making any change, is there a good reason?
Is the system overloaded?

The 2748 is the first AS/400 disk IOP with a fast write cache larger than 4
megabytes.  It also has a reasonably large read cache.  The 6502 and 6522
had a 2 mb cache, the 6512 and 6533 had a 4 mb cache.  In a write-intensive
RAID environment, I think that it is possible to overwhelm a 4 mb cache - I
have some data to support that point of view - but it takes a big machine
and a lot of adds, changes, and deletes.  I saw it on a 12-way Northstar but
only under certain circumstances.

Richard Jackson
mailto:richardjackson@richardjackson.net
www.richardjacksonltd.com
Voice: 1 (303) 808-8058
Fax:   1 (303) 663-4325

-----Original Message-----
From: owner-midrange-l@midrange.com
[mailto:owner-midrange-l@midrange.com]On Behalf Of Chris Bipes
Sent: Monday, July 17, 2000 3:13 PM
To: 'MIDRANGE-L@midrange.com'
Subject: RE: AS/400 UPGRADE


What disk IOP would you recommend?  Or would you recommend added a second
IOP and splitting the drives?  So far, We have had excellent performance.
But then I do not know if we have ever monitored the IOPs performance.

Christopher K. Bipes     mailto:ChrisB@Cross-Check.com
Sr. Programmer/Analyst   mailto:Chris_Bipes@Yahoo.com
CrossCheck, Inc.         http://www.cross-check.com
6119 State Farm Drive    Phone: 707 586-0551 x 1102
Rohnert Park CA  94928 Fax: 707 586-1884

If consistency is the hobgoblin of little minds, only geniuses work here.
Karen Herbelin - Readers Digest 3/2000


-----Original Message-----
From: Richard Jackson [mailto:richardjackson@richardjackson.net]
Sent: Monday, July 17, 2000 1:25 PM
To: MIDRANGE-L@midrange.com
Subject: RE: AS/400 UPGRADE


Chris:

The 6512 IOP can be configured to support 16 arms in 2 RAID sets.
"Handling" 16 arms in a write-intensive environment is another question
altogether.

Beware: the PCI disk IOPs support a maximum of 15 disk arms.

Richard Jackson
mailto:richardjackson@richardjackson.net
www.richardjacksonltd.com
Voice: 1 (303) 808-8058
Fax:   1 (303) 663-4325
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