Date: Tue, 27 Mar 2001 17:16:53 +0930 From: Greg Lehey <grog@lemis.com> To: "Michael C . Wu" <keichii@peorth.iteration.net> Cc: dillon@freebsd.org, fs@freebsd.org, hackers@freebsd.org Subject: Vinum stripe size (was: tuning a VERY heavily (30.0) loaded server) Message-ID: <20010327171653.G1161@wantadilla.lemis.com> In-Reply-To: <20010320111144.A51924@peorth.iteration.net>; from keichii@iteration.net on Tue, Mar 20, 2001 at 11:11:44AM -0600 References: <20010320111144.A51924@peorth.iteration.net>
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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. Greg -- Finger grog@lemis.com for PGP public key See complete headers for address and phone numbers To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
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