From owner-freebsd-current Fri Oct 29 9: 8: 4 1999 Delivered-To: freebsd-current@freebsd.org Received: from yana.lemis.com (yana.lemis.com [192.109.197.140]) by hub.freebsd.org (Postfix) with ESMTP id 7AA35157DA for ; Fri, 29 Oct 1999 09:07:48 -0700 (PDT) (envelope-from grog@lemis.com) Received: from mojave.worldwide.lemis.com ([199.103.141.157]) by yana.lemis.com (8.8.8/8.8.8) with ESMTP id BAA23773 for ; Sat, 30 Oct 1999 01:37:26 +0930 (CST) (envelope-from grog@lemis.com) Message-ID: <19991026110615.51265@mojave.worldwide.lemis.com> Date: Tue, 26 Oct 1999 11:06:15 -0400 From: Greg Lehey To: Geoff Buckingham Cc: Mike Tancsa , freebsd-current@freebsd.org Subject: Re: AMRD (MegaRAID) BIOS rev another other questions References: <3.0.5.32.19991020143339.016e0210@staff.sentex.ca> <19991022140949.A82396@chuggalug.clues.com> <19991024095811.61238@mojave.worldwide.lemis.com> <19991026112647.B95499@chuggalug.clues.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit In-Reply-To: <19991026112647.B95499@chuggalug.clues.com>; from Geoff Buckingham on Tue, Oct 26, 1999 at 11:26:47AM +0100 Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Tuesday, 26 October 1999 at 11:26:47 +0100, Geoff Buckingham wrote: > On Sun, Oct 24, 1999 at 09:58:11AM -0600, Greg Lehey wrote: >> >> Indeed. It's quite easy to put all cylinder groups on a single >> spindle; I've seen reports of up to 80% degradation under these >> circumstances. >> >>> Where sequential read/write performance is not critical you can stripe at >>> cluster size to avoid this. Other wise using an odd number of spindles for >>> a stripe and an even number for a RAID3 or RAID5 or stripeing at an interval >>> which is not a power of two should work (12,24,48,76 etc) >> >> The best I've heard of is 768 kB - 1 sector. This works on Vinum, but >> it seems that most RAID controllers use a somewhat simplistic striping >> algorithm. You might like to try 31 kB or such. This won't make any >> difference with rawio, though. > > I would agree from experiance that 768 KB seems a good selection for vinum > and probably ccd too There's a big difference between 768 kB and 767½ kB. That's the point I was trying to make. With 768 kB, you risk having all your superblocks on one drive. 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-current" in the body of the message