From owner-freebsd-current Mon Dec 10 10:30:48 2001 Delivered-To: freebsd-current@freebsd.org Received: from apollo.backplane.com (apollo.backplane.com [216.240.41.2]) by hub.freebsd.org (Postfix) with ESMTP id A064537B421; Mon, 10 Dec 2001 10:30:11 -0800 (PST) Received: (from dillon@localhost) by apollo.backplane.com (8.11.6/8.9.1) id fBAIU4w47648; Mon, 10 Dec 2001 10:30:04 -0800 (PST) (envelope-from dillon) Date: Mon, 10 Dec 2001 10:30:04 -0800 (PST) From: Matthew Dillon Message-Id: <200112101830.fBAIU4w47648@apollo.backplane.com> To: Wilko Bulte Cc: Mike Smith , Terry Lambert , Joerg Wunsch , freebsd-current@FreeBSD.ORG Subject: Re: cvs commit: src/sys/kern subr_diskmbr.c References: <200112101754.fBAHsRV01202@mass.dis.org> <200112101813.fBAIDKo47460@apollo.backplane.com> <20011210192251.A65380@freebie.xs4all.nl> Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG :> performance without it - for reading OR writing. It doesn't matter :> so much for RAID{1,10}, but it matters a whole lot for something like :> RAID-5 where the difference between a spindle-synced read or write :> and a non-spindle-synched read or write can be upwards of 35%. : :If you have RAID5 with I/O sizes that result in full-stripe operations. Well, 'more then one disk' operations anyway, for random-I/O. Caching takes care of sequential I/O reasonably well but random-I/O goes down the drain for writes if you aren't spindle synced, no matter what the stripe size, and will go down the drain for reads if you cross a stripe - something that is quite common I think. -Matt Matthew Dillon To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message