Date: Thu, 10 May 2001 07:07:53 +0200 (CEST) From: Luigi Rizzo <luigi@info.iet.unipi.it> To: "Brian W. Buchanan" <brian@CSUA.Berkeley.EDU> Cc: hackers@FreeBSD.ORG Subject: Re: fd driver hacking to recover data Message-ID: <200105100507.HAA43359@info.iet.unipi.it> In-Reply-To: <Pine.BSF.4.21.0105092153220.3063-100000@thought.adamantsys.com> from "Brian W. Buchanan" at "May 9, 2001 10:04:34 pm"
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> I have a bunch of old floppy disks with some text files I'd like to > recover. Many of them have errors and are unreadable past a certain point > in the disk. Others I can't read from at all. > > The ones I can't read, period, are all 1.44MB-size floppies. I've tried > dd'ing from /dev/fd0c, /dev/fd0.1440, etc., but exits with "Input/Output > Error" before copying anything. i think you can try dd from the raw device (/dev/rfd) using the "iseek" or "skip" option to jump over the missing sectors. Alternatively, you can use "conv=noerror,sync" to keep reading after errors (the bad blocks are NUL-filled) cheers luigi > The kernel prints: > > fd0c: hard error reading fsbn 0 of 0-31 (ST0 40<abnrml> ST1 1<no_am> ST2 0 > cyl 0 hd 0 sec 1) > > > I've been more successful reading 720K floppies from /dev/fd0.720, but > many of them have errors that stop dd in its tracks, yielding another > Input/Output error. > > The kernel prints: > > fd0c: hard error reading fsbn 1503 of 1488-1503 (ST0 44<abnrml,top_head> > ST1 20<bad_crc> ST2 20<bad_crc> cyl 41 hd 1 sec 10) > > > Since the files on the disks are just text, all I want to do is to be able > to extract as many of the bits on the disk as possible, even if some of > the bits are wrong, and then run strings over it and sort out the > content. I've looked at the floppy driver source and it seems to be > incredibly low-level, i.e. it turns the drive motor on and off, even. Can > someone familiar with the driver give me some pointers as to what I'd have > to modify to let it 1) read those 1.44MB disks, and 2) tolerate data > errors? > > Thanks, > > Brian > > -- > Brian Buchanan brian@CSUA.Berkeley.EDU > -------------------------------------------------------------------------- > FreeBSD - The Power to Serve! http://www.freebsd.org > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-hackers" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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