Date: Sat, 24 Aug 1996 00:08:15 -0700 From: "Michael L. VanLoon" <michaelv@MindBender.serv.net> To: Joe Greco <jgreco@brasil.moneng.mei.com> Cc: michael@memra.com (Michael Dillon), craigs@os.com, freebsd-isp@freebsd.org, mvanloon@microsoft.com Subject: Re: Anyone using ccd (FreeBSD disk striper) for news Message-ID: <199608240708.AAA02076@MindBender.serv.net> In-Reply-To: Your message of Thu, 22 Aug 96 16:50:50 -0500. <199608222150.QAA25222@brasil.moneng.mei.com>
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>Build it for speed and as close to zero latency as possible. Use more disks
>instead of less. Stripe lots of FAST 1GB disks - like the new Hawk 31055's
>- instead of going with larger drives. 2 9ms 1G disks are ALWAYS faster
>than 1 8ms 2G disk, and the price is similar! Go with more SCSI busses.
>NCR controllers are $60 apiece. Get three, and a 10/100 PCI Ethernet
>controller, and you're still only putting out about $350 for your I/O
>controllers.
Have you compared Adaptec 2940UW's with tagged-command-queuing enabled
to these? I found tagged-queuing to be a huge win in some benchmarks
I ran recently when comparing a BusLogic and Adaptec controller. Does
the NCR driver do tagged-command-queuing?
>Use a large stripe size. I use 1 cylinder group. You are not striping for
>bandwidth. You are striping for CONCURRENCY. You _want_ one mechanism to
>be able to handle an _entire_ file access on its own.
Is this something you just deduced, or have you proven this under real
newsfeed conditions? I'm still slightly skeptical -- I think I'd
start by trying smaller interleaves to increase the liklihood of
randomizing the drive accessed per file, going with maybe cluster size
(16K) up to a physical drive cylinder (~600K, probably) per
interleave. But, if you've done extensive testing (and only if you've
done extensive testing) of these alternatives, I'll take your advice
as the direction to go in.
How many drives per controller, and controllers per machine would you
say is "optimum"?
>Don't compromise on RAM. Stuff it. My feeds box has 128MB RAM. The
>readers have 256MB (we had some fun with that though).
What special tricks did you need to do to FreeBSD to make it run in
128MB of RAM? 256MB? Anything?
Did I understand that you're running a 2.2 snapshot? Is there a
particular reason you're using this and not 2.1.5?
Also, what ethernet card has given you the best results (specific
model, please)?
I'm going to be setting up a killer newsfeed-sucking machine at work
to do performance testing against, and I want to wring as much
performance as I can out of this box (It'll be a Dell OptiPlex P5
133MHz -- the rest is up to me).
Any other tips you (or anyone else) would like to share?
-----------------------------------------------------------------------------
Michael L. VanLoon michaelv@MindBender.serv.net
--< Free your mind and your machine -- NetBSD free un*x >--
NetBSD working ports: 386+PC, Mac 68k, Amiga, Atari 68k, HP300, Sun3,
Sun4/4c/4m, DEC MIPS, DEC Alpha, PC532, VAX, MVME68k, arm32...
NetBSD ports in progress: PICA, others...
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