Date: Wed, 3 Feb 1999 17:16:10 +1030 From: Greg Lehey <grog@lemis.com> To: John Saunders <john.saunders@nlc.net.au> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: advice on setting up a Vinum volume Message-ID: <19990203171610.Z1179@freebie.lemis.com> In-Reply-To: <19990203063306.27822.qmail@nhj.nlc.net.au>; from John Saunders on Wed, Feb 03, 1999 at 05:33:06PM %2B1100 References: <19990203073254.C1179@freebie.lemis.com> <19990203063306.27822.qmail@nhj.nlc.net.au>
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On Wednesday, 3 February 1999 at 17:33:06 +1100, John Saunders wrote: > In nlc.lists.freebsd-questions you wrote: >> On Tuesday, 2 February 1999 at 11:48:15 -0600, Glenn Johnson wrote: >>> When you say performance should be acceptable, does that imply that >>> performance would be better if I didn't use a Vinum striped volume? I >>> was considering using the striped volume for /usr/obj and /usr/ports. > >> I'd expect the performance of a striped volume to be better than for a >> non-striped volume *for multiple concurrent access*. What you do on >> /usr/obj and /usr/ports doesn't normally fit that model. I wouldn't >> expect much difference like in this case. > > Sustained performance is much better. On my pair of Quantum 6.4GB drives > they get approx 7MB/s sustained (dd if=/dev/zero of=file bs=262144 > count=1024). With a vinum strip of 256K in size I get sustained > 12.5MB/s. Running squid on this setup I can watch the load being > distributed by running (systat -iostat 1) Interesting. Which version of FreeBSD is this? Are you using the standard vinum, which includes slow debugging aids, or have you compiled them out? > although vinum stats show that one drive seems to be used about 20% > more than the other. I've noticed this too. There's no way this can be a vinum problem (in other words, you should see exactly the same distribution when using ccd). I suspect that it's an incompatibility between ufs and the stripe size. I suspect that you may end up with all super blocks on one drive. It would be interesting to calculate what stripe size would balance the cylinder groups across the drives. Greg -- When replying to this message, please copy the original recipients. For more information, see http://www.lemis.com/questions.html See complete headers for address, home page and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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