Date: Thu, 26 Sep 2002 21:14:26 -0500 (CDT) From: Mike Silbersack <silby@silby.com> To: Sean Farley <sean-freebsd@farley.org> Cc: freebsd-hackers@freebsd.org Subject: Re: Slow I/O responsiveness with UDMA133 Message-ID: <20020926211102.Q9440-100000@patrocles.silby.com> In-Reply-To: <20020926075207.U295-100000@thor.farley.org>
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On Thu, 26 Sep 2002, Sean Farley wrote: > I just do not understand how a 5400 RPM UDMA 33 drive can beat a 7200 > RPM UDMA 133 drive by 33% on sequential output blocks. Rumor has it that newer drives cannot write a single sector at a time, and instead must read a whole cluster of sectors, add in the new sector, and write back the whole cluster. That behavior sounds like it would hurt sequentual performance substantially, as it would become a lot of read-modify-write operations. > > Does the drive support tagged queueing? That should give you the > > benefits of write caching with a little bit more safety. > > I thought only IBM had IDE drives which supported tags. No. The specs > do not mention tags. Hm, I thought other vendors had started to support them, I guess they decided not to. :| I have no idea on what BIOS settings would be optimal. I doubt that they'll make a real performance difference. Mike "Silby" Silbersack To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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