fsck

[soralx at cydem.org]

> > Maybe I can mount a dirty partition..... I just need the data off it... 
> Mount it read-only and get the data off it IMMEDIATELY.  I wouldn't try
> fsck-ing on any disk with even a single read or write error.  Fsck will
> fail if it can't find a real sector to allocate, and I don't think it deals
> well with bad sectors anyway.  Point is:  don't let it.  "dd" the drive
> ASAP and cut your losses...

also, just beware that the OS may panic when reading a corrupt FS (this
happened to me at least once). umount all other slices.
in case it panicks, use verbose cp (`cp -v`) to see which files are being
copied, note those which cause panic, and skip them

i would also suggest to dd the drive's contents, and then and then fool
around with it for some time (in order of a week) to get the most data
off of it. First, determine the cause of the failure (use smartmontools);
if it's electronics, you'll see smth like:

SMART Self-test log structure revision number 1
Num  Test_Description    Status                  Remaining  LifeTime(hours)  LBA_of_first_error
[...]
# 4  Short offline       Completed: electrical failure 90%     13469         127

There's a good chance that the thing might heal itself somewhat (black
magic!). One of the ATA drives I'm using now had this failure, and it
persisted for a few days while I was subjecting the HDD to various
stresses (heat/cold, vibration, intense workout, manufacturer's test
program, etc). Then suddenly, after about a week, it started working,
and still works! (of course, all the data was long rewritten million
times :/)

If the cause is a media defect, I don't believe there's any chance of
recovering anymore data. If it failed because of a 'mild' head-crash,
you'd want to be very careful with the drive, and make a copy ASAP;
don't move it around too much.

[SorAlx]  ridin' VN1500-B2