30 May
2013
30 May
'13
10:35 a.m.
On Thu, 30 May 2013, Steve Merrony wrote:
As I haven't been able to source the microcode for
my MV/2500 I am attempting
to rescue bits/bytes/words from it's 330MB system disk.
Naive use of ddrescue has yielded about 80MB of the disk - does anyone have
any suggestions for improving that ratio?
Also, are there any tools out there for examining partial disk images in
strange formats? :-/
Assuming you are using GNU ddrescue and not dd_rescue from Kurt Garloff,
the info page contains quite a lot of information. You should also use a
logfile since that allows you to 'resume' from a previous partial read.
I was able to fully recover a 4GB CompactFlash card with GNU ddrescue
about a month ago that had errors due to being powered down during a write
operation. I first used ddrescue to build a complete image of the CF card.
I then made a backup copy of the disk image, and used ddrescue's "fill
mode" to fill the "bad" area with NULL characters. I could then repair the
disk image with e2fsck, and used ddrescue to compare the original and
repaired disk images so I could see exactly where the error was. The error
turned out to be in something completely irrelevant, so I ended up with no
data loss whatsoever. After overwriting the CF card to force it back into
a clean state, I then used ddrescue to write the repaired disk image back
to the card. Overall the entire process took quite a few hours, but it
still took far less time than rebuilding the machine from current backups.