Date: Sat, 15 Aug 1998 11:53:23 +0000 From: Mike Smith <mike@smith.net.au> To: Jason Thorpe <thorpej@nas.nasa.gov> Cc: hackers@FreeBSD.ORG Subject: Re: TESTERS WANTED for new ATAPI CD/CDR/CDRW driver. Message-ID: <199808151153.LAA01317@word.smith.net.au> In-Reply-To: Your message of "Sat, 15 Aug 1998 11:30:50 MST." <199808151830.LAA05540@lestat.nas.nasa.gov>
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> On Sat, 15 Aug 1998 09:33:09 +0000 > Mike Smith <mike@smith.net.au> wrote: > > For what it's worth, I don't see much value in treating ATA disks as > > though they were SCSI disks; the overhead in translation is probably > > too high. On the other hand, I'm less sure about things that use the > > ATAPI packet protocol. > > Considering that even SCSI command passthrough works on many ATAPI > disks and CD-ROMS, it really is the right thing to do, and we have > had a LOT of success doing it this way in NetBSD. I'd be curious to know if anyone's measured the cost of the SCSI<->ATA translation for ATA disks, since that's where performance is really an issue. Nobody cares how efficient access to a Zip disk is, but an extra 10% overhead on ATA disk transactions would really hurt. Command passthrough doesn't (can't) work directly, as many fields are different sizes. I think what you mean is that there's no need for any intelligence in the translation, which is fair enough. -- \\ Sometimes you're ahead, \\ Mike Smith \\ sometimes you're behind. \\ mike@smith.net.au \\ The race is long, and in the \\ msmith@freebsd.org \\ end it's only with yourself. \\ msmith@cdrom.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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