Re: [Bug-tar] tar: unable to read LTO4 tapes on a LTO5 drive using tar

[Mark]

On Thu, June 14, 2012 09:01, address@hidden wrote:
> A colleague has got some LTO4 tapes, which are believed to be written
> using a tar command with a switch of -b 1024.
>
> However, we tried tar -b 1024 -tvf /dev/nst0
>
> we are getting io errors.
>
> We put in a blank LTO4 tape, and with that, a simple tar -cvf /dev/nst0
> followed by tar -xvf /dev/nst0 works.
>
> So we cannot make out why we cannot read the LTO4 tapes.

Are you sure the tape was written with 1024-byte blocks?

First make sure you're not in fixed-block mode by doing
  mt -f /dev/nst0 setblk 0

Then try reading with dd. As mentioned you could pipe dd's output into
tar, or just dump the file to disk first. Try
  dd if=/dev/nst0 of=data.bin bs=262144
and see what happens. (The large block size dd argument is hopefully
larger than whatever block size the tape was actually written with.)


-- Mark