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Date:      Thu, 16 Dec 1999 14:08:17 -0500 (EST)
From:      David Gilbert <dgilbert@velocet.ca>
To:        Brad Knowles <blk@skynet.be>
Cc:        David Gilbert <dgilbert@velocet.ca>, Brad Knowles <brad@shub-internet.org>, freebsd-current@FreeBSD.ORG
Subject:   Re: AMI MegaRAID datapoint.
Message-ID:  <14425.14497.356453.187331@trooper.velocet.net>
In-Reply-To: <v0422081bb47ee1f84029@[195.238.1.121]>
References:  <14425.2778.943367.365945@trooper.velocet.net> <v0422081ab47ebe7ceb22@[195.238.1.121]> <14425.6118.899093.621159@trooper.velocet.net> <v0422081bb47ee1f84029@[195.238.1.121]>

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>>>>> "Brad" == Brad Knowles <blk@skynet.be> writes:

Brad> 	It sounds like the second RAID-5 bug listed on the page I
Brad> mentioned:

>>> 28 September 1999: We have seen hangs when perform heavy I/O to
>>> RAID-5 plexes. The symptoms are that processes hang waiting on
>>> vrlock and flswai. Use ps lax to display this information.
>>> 
>>> Technical explanation: A deadlock arose between code locking
>>> stripes on a RAID-5 plex (vrlock) and code waiting for buffers to
>>> be freed (flswai).
>>> 
>>> Status: Being fixed.

Maybe, maybe not.  My crashes have a different signature than your
according to Greg.

Brad> 	I believe that I have seen this bug myself, but in my only
Brad> 	I have never been impressed with the benchmarking that bonnie
Brad> is capable of.  In my experience, rawio is a much better tool,
Brad> because it handles coordinating large numbers of child
Brad> processes, doesn't lose information in communications between
Brad> the parent and the child processes, by-passes all the filesystem
Brad> overhead, etc....

Brad> 	If you want to do filesystem level benchmarking, I've been
Brad> more impressed by what I've seen out of Postmark.

... well... one of the pros that I have heard for bonnie is that you
get a number that is close to what you can expect with
applications... vs. something like rawio that is isolating one system
for intensive testing.  I often use bonnie as a good weathervane of
how fast a "whole system" is with it's disk.

Dave.

-- 
============================================================================
|David Gilbert, Velocet Communications.       | Two things can only be     |
|Mail:       dgilbert@velocet.net             |  equal if and only if they |
|http://www.velocet.net/~dgilbert             |   are precisely opposite.  |
=========================================================GLO================


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