Date: Fri, 31 Jan 2003 14:06:11 -0500 From: Steve Byan <stephen_byan@maxtor.com> To: phk@freebsd.org Cc: freebsd-fs@freebsd.org, tech-kern@netbsd.org Subject: Re: DEV_B_SIZE Message-ID: <1010FEB6-354F-11D7-B26B-00306548867E@maxtor.com> In-Reply-To: <19187.1044039084@critter.freebsd.dk>
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On Friday, January 31, 2003, at 01:51 PM, phk@freebsd.org wrote: > In message <A02737C6-354B-11D7-B26B-00306548867E@maxtor.com>, Steve > Byan writes > : > >>> The only thing that exposes us to risk is we don't know the risk >>> exists, so as long as the fact that a 4k physical sector size is >>> used is not hidden from us, we can adapt. >> >> But would existing code be functionally broken (perhaps with respect >> to >> failure recovery) if it were to not be modified to adapt to a >> different >> physical block size? > > Not broken any worse than because of write-caching. Agreed, but IDEMA is proposing to do this to SCSI drives, too. > >>> Nope. >> >> Really? fsck can recover from losing 4K bytes surrounding the last >> metadata block written? > > If the fragment size is 4k when the filsystem is created, and this > would happen automatically, then there is no window for lossage. But if someone were to plug a new 4K-block disk into a system compiled to use 512 byte block disks, and the SCSI interface were faked to make it appear that the disk could read and write 512-byte blocks, then what happens? IDEMA's notion is that faking 512-byte logical size is good enough to get new disks to work in systems running legacy code. My fear is that it is not so simple. > > The thing we really need is working tagged-queing... Since I believe tagged-queuing works in SCSI, I assume you are asking for it in ATA? Or is there some feature missing from SCSI tagged-queuing that you'd like to see? Regards, -Steve -------- Steve Byan <stephen_byan@maxtor.com> Design Engineer Maxtor Corp. MS 1-3/E23 333 South Street Shrewsbury, MA 01545 (508) 770-3414 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
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