From owner-freebsd-hackers Tue Mar 27 0: 7:15 2001 Delivered-To: freebsd-hackers@freebsd.org Received: from fw.wintelcom.net (ns1.wintelcom.net [209.1.153.20]) by hub.freebsd.org (Postfix) with ESMTP id 20D5637B718; Tue, 27 Mar 2001 00:07:10 -0800 (PST) (envelope-from bright@fw.wintelcom.net) Received: (from bright@localhost) by fw.wintelcom.net (8.10.0/8.10.0) id f2R854f21423; Tue, 27 Mar 2001 00:05:04 -0800 (PST) Date: Tue, 27 Mar 2001 00:05:03 -0800 From: Alfred Perlstein To: Greg Lehey Cc: "Michael C . Wu" , dillon@FreeBSD.ORG, fs@FreeBSD.ORG, hackers@FreeBSD.ORG Subject: Re: Vinum stripe size (was: tuning a VERY heavily (30.0) loaded server) Message-ID: <20010327000503.T9431@fw.wintelcom.net> References: <20010320111144.A51924@peorth.iteration.net> <20010327171653.G1161@wantadilla.lemis.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: <20010327171653.G1161@wantadilla.lemis.com>; from grog@lemis.com on Tue, Mar 27, 2001 at 05:16:53PM +0930 X-all-your-base: are belong to us. Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG * Greg Lehey [010326 23:47] wrote: > On Tuesday, 20 March 2001 at 11:11:44 -0600, Michael C . Wu wrote: > > [Lengthy email, bear with me please, it is quite interesting. > > This box averages 30.0 load with no problems.] > > > > > > > > Average file size is about 4K. /home/bbsusers* is on a vinum > > stripe'd volume with 3 Ultra160 9G 10000RPM drives on sym0 at stripe > > size 256K, Greg: I know this should be a prime number, > > No, there's no requirement for it to be a prime number. The only > problem is that with 32 MB cylinder groups and a power of two stripe > size and subdisk count, you end up with all the superblocks on one > subdisk, which is a performance issue. Choose the stripe size so that > the superblocks are roughly evenly distributed. > > > can we safely use <150K stripe sizes? > > Safely, yes. But as somebody else has observed, you are probably disk > I/O bound. Reducing the stripe size will tend to increase the disk > load, though probably not very much if your files are all 4 kB. I'd > go for something like 273 kB stripes. Do you think it'd be worth it to have vinum carp about what may be a non optimal stripe size? "Warning N is probably a bad idea for a stripe size, see docs" -- -Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org] Daemon News Magazine in your snail-mail! http://magazine.daemonnews.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message