Date: Tue, 7 May 1996 15:34:15 +0930 (CST) From: Michael Smith <msmith@atrad.adelaide.edu.au> To: rnordier@iafrica.com (Robert Nordier) Cc: msmith@atrad.adelaide.edu.au, hackers@freebsd.org Subject: Re: dosfsck anyone? Message-ID: <199605070604.PAA20167@genesis.atrad.adelaide.edu.au> In-Reply-To: <199605070501.HAA01634@eac.iafrica.com> from "Robert Nordier" at May 7, 96 07:01:19 am
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Robert Nordier stands accused of saying: > > > > Not enough space to scribble on, can't make repairs! > > Either abort and make some space, or answer yes to the following question. > > DISCARD ALL AMBIGUOUS FILE DATA [yn]? > > > > Hmm. This is lessening my reservations, but I'm still not 100% > convinced that using 'free' clusters is the way to go. (Which is also > why I'd prefer a pre-slotted 'lost.fnd'.) I'm worried about cases where > the FAT is badly corrupted ... which really is probably why we have all > the cross-links, anyway. Hmm. I guess it depends on how 'smart' you want to get about it. It's fairly easy to determine which sectors in the FAT have had the Big A; if you look at a "typically" corrupted filesystem, there'll be problems related to entries in one or more contiguous sectors. If I recall correctly, DOS' normal allocation strategy tends to use the clusters towards the end of the filesystem last. A combination of these two would tend to imply that you could generally expect to pick up free clusters from the end of the filesystem, and that it should be possible to determine whether the FAT in that area had been damaged. > hierarchy, and this just doesn't apply in the DOS world ... where > designing "a better disk defrag utility" seems like a neat learn C++ > project. 8( Yecch. I tried (several times) to write a 'dosfsck'-style program for the Atari ST, which uses essentially the same filesystem layout. It was one of the most frustrating and scarring parts of my early programming days 8( (None of the commercial tools was particularly good, and the filesystems were sufficiently different that you couldn't just move it to a DOS machine and hit it with 'chkdsk'.) > Robert Nordier -- ]] Mike Smith, Software Engineer msmith@atrad.adelaide.edu.au [[ ]] Genesis Software genesis@atrad.adelaide.edu.au [[ ]] High-speed data acquisition and (GSM mobile) 0411-222-496 [[ ]] realtime instrument control (ph/fax) +61-8-267-3039 [[ ]] Collector of old Unix hardware. "Where are your PEZ?" The Tick [[
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