Date: Thu, 21 Sep 2000 08:15:50 -0700 From: Stephen Byan <Stephen.Byan@quantum.com> To: "'Justin Gibbs'" <gibbs@plutotech.com>, Stephen Byan <Stephen.Byan@quantum.com> Cc: mbendiks@eunet.no, Stephen Byan <Stephen.Byan@quantum.com>, fs@FreeBSD.ORG, sos@FreeBSD.ORG, freeBSD-scsi@FreeBSD.ORG Subject: RE: disable write caching with softupdates? Message-ID: <8133266FE373D11190CD00805FA768BF055BD1D7@shrcmsg1.tdh.qntm.com>
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Justin Gibbs [mailto:gibbs@plutotech.com] wrote: > > Without write caching, you pay one disk rotation for each > sequential write. > > This should not be the case if you are allowed to overlap > commands. The > only penalty should be increased latency in seeing a write complete. You're correct. I was writing with respect to ATA drives, of which I believe only IBM's support write queuing, so I overlooked the case where queuing is available. I'm not that familiar with ATA in practice; the spec for ATA queuing looked sufficiently convoluted (i.e. a kludge) that it wasn't obvious to me that it would be a performance win to implement it. Regards, -Steve To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
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