Xref: utzoo comp.unix.wizards:10937 comp.unix.questions:9109
Path: utzoo!attcan!uunet!yale!husc6!hscfvax!pavlov
From: pavlov@hscfvax.harvard.edu (G.Pavlov)
Newsgroups: comp.unix.wizards,comp.unix.questions
Subject: Re: ultrix 2.0 disk throughput
Keywords: ultrix 2.0, microvaxII, disk throughput
Message-ID: <616@hscfvax.harvard.edu>
Date: 6 Sep 88 02:15:34 GMT
References: <3591@phoenix.Princeton.EDU> <615@hscfvax.harvard.edu>
Organization: Health Sciences Computing Facility, Harvard University
Lines: 24

In article <615@hscfvax.harvard.edu>, pavlov@hscfvax.harvard.edu (G.Pavlov) writes:
>   The problem is the QD32 controller.  The only solution is to replace it with
>   someone else's.You may want to try to obtain restitution from Emulex. Good
>   luck. We finally did, but it required a massive effort: at least 40 hours on
>   the phone, over a period of 5 months, involving at least 10 Emulex employees..  
> 
    Judging by mail to me, there is interest in more information on this.  I
    can only tell you what I was told by Emulex; will keep it brief.
   
    The problem appears to be that DEC decreased the timeout interval on disk
    requests.  The QD series emulates the MSCP protocol in microcode and does
    not reply to the cpu quickly enough, thus forcing frequent timeouts.

    The problem supposedly applies to all current QD series controllers.  A
    new generation, to be available Reasonably Soon Now, is claimed by Emulex
    to be quick enough to overcome the problem.

    We are awaiting a set of Dilog 256 controllers as replacements.  We have
    had one in-house for the past month for eveluation.  It appears to be 
    moderately faster than the Emulex QD32.  But, as with the QD32, its per-
    formance (in our shop) with one disk is fine but so-so with two.  

>    greg pavlov, fstrf, amherst, ny 
>    716-834-0900