Re: dd hangs when attempting to access a tape drive

[Jim Meyering]

Thanks for the detailed report.
To narrow it down a little more, please run dd via strace, e.g.,

  strace -o log dd if=file.name of=/dev/nst0 bs=32 count=1

Then, at least, we'll have a good idea which syscall is causing
the trouble.

On general principle, a process that cannot be killed
via `kill -9' suggests a kernel bug.  But even if that's
the case, we may want to make dd avoid triggering it.

Curtis J Blank <address@hidden> wrote:
> I've got a problem were dd hangs attempting to access a tape drive, this
> used to work fine. The only change is going to the 2.6 kernel, SuSE's 9.3
> 2.6.11.4-21.9 to be exact. The dd command is (this is all done as root):
>
> dd if=file.name of=/dev/nst0 bs=32 count=1
> or
> dd if=/dev/nst0 bs=32 count=1
>
> If it's done command line you cannot ^C out of it, and command line or in
> a cron job you cannot kill -9 the process, the only way to get rid of it
> is to reboot. mt can access the drive just fine, tar can read and write
> the drive just fine.
...