Date: Wed, 26 Jul 1995 13:12:38 +0200 (MET DST) From: J Wunsch <j@uriah.heep.sax.de> To: freebsd-current@FreeBSD.org (FreeBSD-current users) Subject: Re: Interesting NFS problem with -current Message-ID: <199507261112.NAA13745@uriah.heep.sax.de> In-Reply-To: <9507252053.AA17127@cs.weber.edu> from "Terry Lambert" at Jul 25, 95 02:53:09 pm
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As Terry Lambert wrote: > > We're worried about media changes, right? Ones that don't involve > remounting the same media? Yup. > There's supposed to be a unique disk ID generated from the manufacturer > and a manufacturer ID for that. > > In practice, this almost never happens. Ask Jordan why. 8-). :-/ It won't help for other removable media either (e.g. ZIP drives), and i guess (without looking into it) that the current sd driver doesn't handle this case very gracefully at all. > I think the MD5 checksum is probably the best mechanism. Yup. Or some other CRC mechanism, does somebody know whether there's already something available in the kernel? > I'd use the root directory blocks, however, which means generating > it at mount time. There's no guarantee that there will even be data > other than a potentially non-unique header at the front of the disk. The root directory, or the media descriptor (or whatever it is actually named; i mean the bytes starting at 0x8000). -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ Never trust an operating system you don't have sources for. ;-)
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