Date: Tue, 27 Mar 2001 00:05:03 -0800 From: Alfred Perlstein <bright@wintelcom.net> To: Greg Lehey <grog@lemis.com> Cc: "Michael C . Wu" <keichii@peorth.iteration.net>, 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> In-Reply-To: <20010327171653.G1161@wantadilla.lemis.com>; from grog@lemis.com on Tue, Mar 27, 2001 at 05:16:53PM %2B0930 References: <20010320111144.A51924@peorth.iteration.net> <20010327171653.G1161@wantadilla.lemis.com>
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* Greg Lehey <grog@lemis.com> [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.] > > > > <snip> > > > > 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
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