Disk IOA (Was RE: AS/400 UPGRADE)

["Allen, Stu" <sallen@xxxxxxxxxxxx>]

After using the 2748 card and comparing it to a 2741 in a system that isn't
particularly loaded with I/O, the difference is still immediately apparent.
I have no quantifyable data to support this, it just "felt" quicker all
round.  The card also looks a lot more modern!

However (and the reason that i have no quantifyable data), i'm personally
not convinced that IBM's hardware testing has been 100% with this card.
Its incompatable with a 2809 combined function IOP, and also with a 9329 PCI
cage.  (this resulted in me going back to the 2741)  These and other H/w
issues may well have been all found/resolved now, but i'd definately talk to
your CE about it.

Regards,
Stuart
                                                             
Stuart Allen
European Systems Analyst,  Fellowes
mailto:sallen@fellowes.com

> -----Original Message-----
> From: Richard Jackson [SMTP:richardjackson@richardjackson.net]
> Sent: Thursday, July 20, 2000 8:32 PM
> To:   MIDRANGE-L@midrange.com
> Subject:      RE: AS/400 UPGRADE
> 
> 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
> 
> 
> 
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