From owner-freebsd-hackers Mon Mar 26 23:47: 4 2001 Delivered-To: freebsd-hackers@freebsd.org Received: from wantadilla.lemis.com (wantadilla.lemis.com [192.109.197.80]) by hub.freebsd.org (Postfix) with ESMTP id 08BA437B71D; Mon, 26 Mar 2001 23:46:55 -0800 (PST) (envelope-from grog@lemis.com) Received: by wantadilla.lemis.com (Postfix, from userid 1004) id 70CE06A90D; Tue, 27 Mar 2001 17:16:53 +0930 (CST) Date: Tue, 27 Mar 2001 17:16:53 +0930 From: Greg Lehey To: "Michael C . Wu" 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> References: <20010320111144.A51924@peorth.iteration.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: <20010320111144.A51924@peorth.iteration.net>; from keichii@iteration.net on Tue, Mar 20, 2001 at 11:11:44AM -0600 Organization: LEMIS, PO Box 460, Echunga SA 5153, Australia Phone: +61-8-8388-8286 Fax: +61-8-8388-8725 Mobile: +61-418-838-708 WWW-Home-Page: http://www.lemis.com/~grog X-PGP-Fingerprint: 6B 7B C3 8C 61 CD 54 AF 13 24 52 F8 6D A4 95 EF Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG 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. 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-hackers" in the body of the message