From owner-freebsd-current Wed Jul 26 05:52:51 1995 Return-Path: current-owner Received: (from majordom@localhost) by freefall.cdrom.com (8.6.11/8.6.6) id FAA18705 for current-outgoing; Wed, 26 Jul 1995 05:52:51 -0700 Received: from irz301.inf.tu-dresden.de (irz301.inf.tu-dresden.de [141.76.1.11]) by freefall.cdrom.com (8.6.11/8.6.6) with SMTP id FAA18629 for ; Wed, 26 Jul 1995 05:52:29 -0700 Received: from sax.sax.de by irz301.inf.tu-dresden.de with SMTP (5.67b+/DEC-Ultrix/4.3) id AA09870; Wed, 26 Jul 1995 14:52:11 +0200 Received: by sax.sax.de (8.6.12/8.6.12-s1) with UUCP id OAA09080 for freebsd-current@FreeBSD.org; Wed, 26 Jul 1995 14:52:06 +0200 Received: (from j@localhost) by uriah.heep.sax.de (8.6.11/8.6.9) id NAA13745 for freebsd-current@FreeBSD.org; Wed, 26 Jul 1995 13:12:39 +0200 From: J Wunsch Message-Id: <199507261112.NAA13745@uriah.heep.sax.de> Subject: Re: Interesting NFS problem with -current To: freebsd-current@FreeBSD.org (FreeBSD-current users) Date: Wed, 26 Jul 1995 13:12:38 +0200 (MET DST) Reply-To: freebsd-current@FreeBSD.org (FreeBSD-current users) In-Reply-To: <9507252053.AA17127@cs.weber.edu> from "Terry Lambert" at Jul 25, 95 02:53:09 pm Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch) X-Phone: +49-351-2012 669 X-Mailer: ELM [version 2.4 PL23] Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Content-Length: 1140 Sender: current-owner@FreeBSD.org Precedence: bulk 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. ;-)