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Date:      Tue, 2 May 2000 00:07:33 +0200
From:      Brad Knowles <blk@skynet.be>
To:        "Brandon D. Valentine" <bandix@looksharp.net>, Mark Powell <M.S.Powell@salford.ac.uk>
Cc:        Joe Karthauser <joe@pavilion.net>, freebsd-stable@FreeBSD.ORG
Subject:   Re: How good is AMI MegaRAID support?
Message-ID:  <v04220805b533ae83fa7a@[195.238.24.94]>
In-Reply-To: <Pine.BSF.4.21.0004291208080.20399-100000@turtle.looksharp.net>
References:  <Pine.BSF.4.21.0004291208080.20399-100000@turtle.looksharp.net>

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At 12:31 PM -0400 2000/4/29, Brandon D. Valentine wrote:

>  I can definitely appreciate that.  The RAID solution of choice for
>  FreeBSD appears to be SCSI-SCSI RAID adapters as utilized on
>  wcarchive.cdrom.com and ftp.freesoftware.org -- the two busiest ftp
>  archives around and consequently the two busiest disk subsystems around.

	The testing I've done so far confirms what Greg Lehey and 
everyone else has been telling me all this time -- dedicated RAID 
controllers just really can't keep up with a good software solution 
(such as vinum, or even ccd) and modern hardware.  It takes a lot 
longer to develop all the custom hardware to put into a RAID 
controller, and main CPU speeds have been increasing so fast, that 
it's quicker and easier to do it all in software these days.


	Even the megabuck Comparex/Hitachi mainframe-style RAID array 
that I've been pounding the snot out of for weeks doesn't reach the 
performance levels of the software RAID configuration that Joe Greco 
built on top of Adaptec controller and bare 50GB 7200 RPM drives (for 
his 1.8TB news spool server), and I have 10kRPM drives and can throw 
as much as 4GB of on-board controller RAM at the problem.  I can get 
reasonably close to his levels of performance, but I haven't been 
able to equal them.

	In fact, to come anywhere *close* to the levels of performance 
that Joe has previously mentioned, I've had to add software RAID 0+1 
(in the form of vinum) on top of the hardware RAID-5 (we tested the 
other forms of RAID, there doesn't seem to be any noticeable speed 
improvement), so that you are striped both horizontally and 
vertically.

--
   These are my opinions -- not to be taken as official Skynet policy
======================================================================
Brad Knowles, <blk@skynet.be>                || Belgacom Skynet SA/NV
Systems Architect, Mail/News/FTP/Proxy Admin || Rue Colonel Bourg, 124
Phone/Fax: +32-2-706.13.11/12.49             || B-1140 Brussels
http://www.skynet.be                         || Belgium


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