Re: [Dump-users] Saving that *last* tape that turns out bad...

[Steve B. <fb7...@sn...>]

If a tape is nearly unreadable (or completely unreadable in parts)
restore may choke even with -y.  Another option might be to find
enough temp space on disk to hold an image of that tape and use a data
recovery tool like "dd_rescue"
(http://www.garloff.de/kurt/linux/ddrescue) to pull what you can off
the tape to a disk image file.  It will fill in the areas its unable
to read on the source tape with zeroes in the image file.  If this is
within file data, the recovered files will be filled with unexpected
zeroes. If it's within the metadata of the dump itself, you may still
have problems restoring (e.g. restore coredumps, etc.)

For example:

# dd_rescue -A /dev/nst0 /big_disk/bad_tape.img

(Note that dd_rescue doesn't use if= or of= and relies on the
parameter position to identify the input and output.  Best to avoid
getting them mixed up.)

  -- Steve