Date: Tue, 19 Nov 1996 22:39:18 +0100 (MET) From: J Wunsch <j@uriah.heep.sax.de> To: freebsd-scsi@FreeBSD.org (FreeBSD SCSI list) Cc: peter@taronga.com Subject: Re: Drive with 1024 byte logical blocks Message-ID: <199611192139.WAA09422@uriah.heep.sax.de> In-Reply-To: <199611191226.EAA01372@freefall.freebsd.org> from barry at "Nov 19, 96 07:18:00 am"
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As barry wrote: > John Gumb and My self are about to submit a patch against > 2.2 that supports 512, 1024 and 2048 byte sectors for MO. > (The algorithms scale able 2048 trivially) Why only these three sector sizes? :-) > Specifically we have msdosfs and ufs fully working on > 2048 byte MO media. We installed the 1006 snap from 2048 byte > MO media. The code changes are small. That surprises me. The fd driver has support for sector sizes between 128 and 1024 bytes for ages now, but last time i've been checking, i couldn't use 1024 bytes for UFS. Neither can i on my 1024-byte formatted media, since i cannot even disklabel them. (Sector sizes < 512 byte will eventually work since the kernel `thinks' in DEV_BSIZE chunks so multiple physical sectors will be processed at once.) > In the driver we did not fight the DEV_BSIZE assumption. All > we do is scale block number by the ratio of the real sector size > over DEV_BSIZE. That's basically the same approach the `fd' driver is taking, though it has to deal with the hardware sector size either smaller, equal, or larger than DEV_BSIZE. -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE Never trust an operating system you don't have sources for. ;-)
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