Date: Wed, 10 Dec 1997 14:05:19 -0800 From: Julian Elischer <julian@whistle.com> To: Jeremy Nelson <jnelson@acronet.net> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: Figuring out why my filesystems spontaneously broke Message-ID: <348F121F.28CC1042@whistle.com> References: <199712101713.LAA04378@nemesis.acronet.net>
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Jeremy Nelson wrote:
>
> After doing a non-component related hardware maintanance (replaced the
> fan in my power supply), i booted up the machine. It booted ok, I logged
> in, started X windows and pppd. At an xterm, i 'cd'd into a subdirectory,
> and did an 'ls'. The machine froze for about 15 seconds and rebooted.
That's probably while the disk was having a hernia.
what is your layout? (disklabel/fdisk) output..
>
> So i move the harddrive to another machine that i know is working ok.
> The harddrive appears to have lost its primary superblock. No problem, i'll
> use a backup superblock. Fsck emits hundreds of DUP and BAD errors, and
> a few various errors about "EXCESSIVE DUP BLKS", "INCORRECT BLOCK COUNT",
> After making it through pass 1, pass 2 says that a few first-level directories
> are empty. It then dies when it cant find an inode. Both the / partition
> (partition a) and the /usr partition (partition e) have the exact same damage
> signature.
sounds like
one of:
(in increasing order of likelyhood)
1/ the drive remapped a whole bunch of blocks
2/ the drive FORGOT that it had remapped a whole bunch of blocks.
3/ the drive was writing bad data on every write you asked it to do.
>
> All of the file data is still there ('dd' has no problem finding it on the
> raw devices), and disklabel(8) shows that the disk label is still intact.
> Since *both* of the fs's went down and since all the data still seems to
> be there, that would indicate that it wasnt a hardware failure. Nevertheless,
> as someone on #freebsd suggested, my filesystems are toast.
>
> This then is a two part question:
> 1) Is there any "easy" way to recover the data without having to resort to
> my backups which i have to confess are probably a bit older than they
> should be?
we can maybe do some tests using un-used sectors and see if you can
write to them.
(simple C program.. open raw disk
lseek to free block (e.g. block 2?)
write pattern..
close device,
check if pattern is on device..
> 2) What might have happened? Is there something i can do to avoid having
> it happen again?
no idea..
>
> System specifics:
> * 486/66, 40 megs of ram, a Conner CFS1621A IDE drive, generally the rest of
> my system componants are unspectacular (built from parts).
> * FreeBSD 2.2.2 (built from CD sources) The machine has been in contiuous
> service since 1994 through a variety of harddrives and systems. This
> particular harddrive has been running FreeBSD happily for about 18 months
> now. I do not mount my drives async.
>
> Thanks to anyone who might be willing to offer help or suggestions.
> Thanks to everyone for their hard work. I (and lots of others) appreciate it.
>
> Jeremy Nelson
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