From owner-freebsd-scsi Fri Apr 7 8:30:50 2000 Delivered-To: freebsd-scsi@freebsd.org Received: from panzer.kdm.org (panzer.kdm.org [216.160.178.169]) by hub.freebsd.org (Postfix) with ESMTP id 9F54937BEDD for ; Fri, 7 Apr 2000 08:30:44 -0700 (PDT) (envelope-from ken@panzer.kdm.org) Received: (from ken@localhost) by panzer.kdm.org (8.9.3/8.9.1) id JAA19624; Fri, 7 Apr 2000 09:29:55 -0600 (MDT) (envelope-from ken) Date: Fri, 7 Apr 2000 09:29:55 -0600 From: "Kenneth D. Merry" To: Stephen Byan Cc: freebsd-scsi@FreeBSD.ORG Subject: Re: newfs on IBM disks slower than Seagate disks? Message-ID: <20000407092955.A19590@panzer.kdm.org> References: <8133266FE373D11190CD00805FA768BF02EE9F64@shrcmsg1.tdh.qntm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 1.0i In-Reply-To: <8133266FE373D11190CD00805FA768BF02EE9F64@shrcmsg1.tdh.qntm.com>; from Stephen.Byan@quantum.com on Fri, Apr 07, 2000 at 06:39:01AM -0700 Sender: owner-freebsd-scsi@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On Fri, Apr 07, 2000 at 06:39:01 -0700, Stephen Byan wrote: > Does the FreeBSD SCSI subsystem set the FUA bit in the CDB for UFS metadata > writes? If so, then data integrity with WCE=1 is probably no worse than for > WCE=0, since the filesystem is caching non-metadata writes anyway. > > If UFS and CAM haven't made arrangements to hint which disk writes are > precious, then I think you're best off setting WCE=0, unless your system and > your disks are on a UPS. CAM doesn't set the FUA bit on metadata writes because it doesn't currently have a way to distinguish between metadata and normal data. Ken -- Kenneth Merry ken@kdm.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message