Date: Fri, 31 Jan 2003 11:55:33 -0800 From: "Jamey Kirby" <jkirby@storagecraft.com> To: "'Julian Elischer'" <julian@elischer.org>, "'Steve Byan'" <stephen_byan@maxtor.com> Cc: <phk@FreeBSD.ORG>, <freebsd-fs@FreeBSD.ORG>, <tech-kern@netbsd.org> Subject: RE: DEV_B_SIZE Message-ID: <000601c2c962$c04aa2d0$0300a8c0@jkirbydesk> In-Reply-To: <Pine.BSF.4.21.0301311144370.45015-100000@InterJet.elischer.org>
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Who will do the translation? Will there be a device driver that makes the 4K disk look like a 512 byte disk? If so, the device driver would have to pre-read the 4K, modify the 512 byte section and re-write the entire 4K. This would kill performance. If this will be handled in the drive, the same sort of logic must be employed and surly there will be a performance problem; unless the drive will be able to write the 512 bytes without a pre-read. How easy is it to change the firmware in the drive to make it a 4K block drive? I would be willing to tinker with a 4K drive and provide some feedback. Jamey -----Original Message----- From: owner-freebsd-fs@FreeBSD.ORG [mailto:owner-freebsd-fs@FreeBSD.ORG] On Behalf Of Julian Elischer Sent: Friday, January 31, 2003 11:49 AM To: Steve Byan Cc: phk@FreeBSD.ORG; freebsd-fs@FreeBSD.ORG; tech-kern@netbsd.org Subject: Re: DEV_B_SIZE One thign I thought of is that it is not uncommon to 'dd' an entire filesystem from one partition to another. If we create a filesystem that is 'aligned' and we copy it to be 'unalligned', we'd have a sudden performance drop for no immediatly obvious reason. What was one write, would become a 2-sector read, modify and 2-sector write. Especially when copying from one failing drive to another with slightly different characteristics. The idea isn't bad but I think it should be sold as a 4k sector drive, with small print saying it can handle 512byte IO instead of the other way around. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
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