On 8/31/22 15:35, David Wright wrote:
On Wed 31 Aug 2022 at 14:02:19 (-0700), David Christensen wrote:
On 8/31/22 06:25, ppr wrote:
I would appreciate advice from the community about a failing hard drive.
When booting up, the computer complained about /dev/sdb, which is
a ext4 HDD with data (not the computer main disk). dmesg shows
`AE_NOT_FOUND` and `failed command: READ FPDMA QUEUED` messages
(full dmesg log at https://hastebin.com/raw/jebelileru).
It has finally booted after trying unsuccessfully to start /dev/sdb.
Comment out the /etc/crypttab and/or /etc/fstab entries for the failed
drive. When you mount the drive, mount it read only.
I don't think it's wise to mount this disk at all, and certainly not
before everything that can be rescued from it has been obtained and
copied/archived.
First sentence -- You don't want the OS to access the drive on the next
boot.
Second sentence -- I should have prefaced that with "after ddrescue has
finished".
Consider doing the work in chunks. You
should already have sectors 0- 33 GB. Skip 33 GB and/or 34 GB. Do
35-100 GB. Then, 100-200 GB, 200-300 GB, 300-400 GB, etc.. Get the
good sectors first. Do the problem sectors last.
Agreed, though ddrescue should be able to do this more flexibly, and
automatically, with -K.
RTFM [1], I don't know if I would use -K. Take a look at the examples
given at the end of section "4 Algorithm" and in "10 A small tutorial
with examples" (examples 3 and 5 look relevant to the OP).
David
[1] https://www.gnu.org/software/ddrescue/manual/ddrescue_manual.html
