Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!killer!mjbtn!raider!root
From: root@raider.UUCP (Bob Reineri)
Newsgroups: comp.sys.hp
Subject: Disc Cacheing
Keywords: HP3000,CACHE
Message-ID: <9@raider.UUCP>
Date: 29 Aug 88 01:34:04 GMT
Organization: RaiderNet Public Access, Murfreesboro, TN
Lines: 29

Though this newsgroup seems oriented more toward the technical HP systems, :-)
I couldn't find any other group to post in. Please bear with me if I'm slighty
off the subject matter.

I am the system manager of an HP3000 series 70, and my question deals with the
perfomance of disc cacheing on this system.

We are a highly interactive environment, with about 70 on-line users on a 
typical day. Much of he work they perform involves  Image databases. I am
getting about a 69% reduction in the number of physical I/O's using the
cacheing system but the write hit (ie,process stops / cache requests) is
abnormally high, on the order of 20 percent. I have tried adjusting both the
sequential and random fetch quantums all over the place, to no avail. I can
get no better performance. One thing I did notice is that the system disc,
LDEV 1, usually has about a 100 % write hit rate ! 

Oh yes, we are running five discs on the system; LDEVS 1 and 2 are 7937
Eagle drives, and the other three are 7935's (404 mb). Any help would be
greatly appreciated.

P.S - IS there a newsgroup for HP's MPE based systems ? 


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