Re: disk cache batteries -- MIDRANGE-L

Jim,

Well the i810 was announced in Feb 2003 so it can't be much more than 2 years old (though you could have migrated older parts)..

No matter what the age, however, if the system flags the cache battery as 'dead' it no longer uses any on board cache in that controller. This causes all I/O's to write through to the drives. The difference during light I/O loads is almost always noticeable, during heavy I/O load the difference is usually dramatic. If you get near the system you will hear the drives going completely berserk and statistics could show the drives 80 or more % busy. Anything over 40% busy consistently is bad, over 60% is very bad, over 80% oh boy. I would certainly believe double or even triple the response times with failed batteries, especially if there is only one controller in the system.

 - Larry

Jim Franz wrote:

We finally got thru our fix of disk cache batteries (iSeries 810 only perhaps 4 years old). The only clue we had was that the system became extremely slow during a conversion test, running about 3 times slower. The CE claimed it shouldn't have hit us that hard. I think otherwise - we were running large cpylib, many chgpf's of big files, and adding 7 gig of files w/RPG to existing 10 gig. Manager asking if I can prove it was the batteries (this was our final test before go-live). Can anyone else confirm losing cache batteries could cause such an effect?
btw- our only clue of hardware problem was wrkdsksts & F11 screen showed disks in 
"degraded" status. After an ipl, we did get following 2 msgs in qsysopr queue:
* *Attention*  Contact your hardware service provider now.
Message ID . . . . . . :   CPPEA12       Severity . . . . . . . :   99
A critical system hardware problem has occurred. Critical Message Handler
   has been run.
Message ID . . . . . . :   CPP8988       Severity . . . . . . . :   90
jim franz

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