Date: Fri, 27 Oct 2006 22:03:06 -0400 From: Martin Cracauer <cracauer@cons.org> To: "Kenneth D. Merry" <ken@kdm.org> Cc: freebsd-scsi@freebsd.org, Martin Cracauer <cracauer@cons.org> Subject: Re: Why is SCSI so much faster with the write cache off (than ATA)? Message-ID: <20061028020306.GA93408@cons.org> In-Reply-To: <20061027220450.GA78909@nargothrond.kdm.org> References: <20061027214011.GB86642@cons.org> <20061027220450.GA78909@nargothrond.kdm.org>
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Kenneth D. Merry wrote on Fri, Oct 27, 2006 at 04:04:50PM -0600: > 10 years ago, ATA disks didn't do tagged queueing, but SCSI disks did. I actually had used some of the rare IBM drives and the Intel 440BX chipset that did support it at the time. But some bit must have been missing. > Now, SATA disks have tagged queueing and also NCQ. In theory those should > work well. Is tagged queueing enabled on the ATA disks you're testing? Is > it the old-style queueing or NCQ? I was done on an NVidia SATA controller, so neither would be available. Very interesting. Now that I think about it all makes sense. Thanks, guys. Martin -- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Martin Cracauer <cracauer@cons.org> http://www.cons.org/cracauer/ FreeBSD - where you want to go, today. http://www.freebsd.org/
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