Date: Fri, 7 Apr 2000 09:29:55 -0600 From: "Kenneth D. Merry" <ken@kdm.org> To: Stephen Byan <Stephen.Byan@quantum.com> Cc: freebsd-scsi@FreeBSD.ORG Subject: Re: newfs on IBM disks slower than Seagate disks? Message-ID: <20000407092955.A19590@panzer.kdm.org> In-Reply-To: <8133266FE373D11190CD00805FA768BF02EE9F64@shrcmsg1.tdh.qntm.com>; from Stephen.Byan@quantum.com on Fri, Apr 07, 2000 at 06:39:01AM -0700 References: <8133266FE373D11190CD00805FA768BF02EE9F64@shrcmsg1.tdh.qntm.com>
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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
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