From owner-freebsd-questions Mon Mar 20 10:52:56 2000 Delivered-To: freebsd-questions@freebsd.org Received: from yana.lemis.com (yana.lemis.com [192.109.197.140]) by hub.freebsd.org (Postfix) with ESMTP id 584B837B9A9 for ; Mon, 20 Mar 2000 10:47:25 -0800 (PST) (envelope-from grog@mojave.worldwide.lemis.com) Received: from mojave.worldwide.lemis.com ([216.88.157.130]) by yana.lemis.com (8.8.8/8.8.8) with ESMTP id FAA12890 for ; Tue, 21 Mar 2000 05:17:06 +1030 (CST) (envelope-from grog@mojave.worldwide.lemis.com) Received: (from grog@localhost) by mojave.worldwide.lemis.com (8.9.3/8.9.3) id KAA01546; Fri, 17 Mar 2000 10:18:03 -0800 (PST) (envelope-from grog) Date: Fri, 17 Mar 2000 10:18:03 -0800 From: Greg Lehey To: Michael Hughes Cc: freebsd-questions@FreeBSD.ORG Subject: Re: vinum strip size Message-ID: <20000317101803.I604@mojave.worldwide.lemis.com> Reply-To: Greg Lehey References: <200003171417.IAA14294@logroad.bridge.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 1.0i In-Reply-To: <200003171417.IAA14294@logroad.bridge.com>; from mhughes@logroad.bridge.com on Fri, Mar 17, 2000 at 08:17:10AM -0600 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 Organization: LEMIS, PO Box 460, Echunga SA 5153, Australia Phone: +61-8-8388-8286 Fax: +61-8-8388-8725 Mobile: +61-41-739-7062 Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Friday, 17 March 2000 at 8:17:10 -0600, Michael Hughes wrote: > Is there an easy way to come up with the strip size to use when striping > disks? No. A number of factors influence the stripe size: 1. You want a stripe large enough that any one I/O will normally fall on a single disk. This maximizes the subsystem bandwidth (in other words, it maximizes performance as seen from the total throughput perspective). 2. You want a stripe size which will ensure even distribution of the ufs superblocks across all subdisks of the plex. Getting (1) is easy: make it at least 256 kB. Getting (2) depends on the number of subdisks. I've written a program for it, but it's not really ready for prime time yet. The important thing is to recognize that cylinder groups are almost invariably 32 MB in size, so any power of two stripe size will give you the worst case situation and put all the superblocks on a single subdisk. Greg -- When replying to this message, please copy the original recipients. For more information, see http://www.lemis.com/questions.html 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-questions" in the body of the message