skip bad block in QIC-150 tar

[Ted Mittelstaedt]

> -----Original Message-----
> From: owner-freebsd-questions at freebsd.org
> [mailto:owner-freebsd-questions at freebsd.org]On Behalf Of
> freebsd at dreamchaser.org
> Sent: Thursday, November 01, 2007 11:10 AM
> To: freebsd-questions at freebsd.org
> Subject: skip bad block in QIC-150 tar
> 
> 
> I'm trying to recover some files from a 5 yr old tar on a QIC-150 tape.
> 
> Unfortunately, there's a bad block on the tape;
>    tar barfs and quits when it gets to it:
> tar: Unrecognized archive format: Inappropriate file type or format
> 
> I managed to get a complete directory listing using tar t on my first
> attempt, before the tape became unreadable; it had to work at it but
> apparently managed to eventually get the block read.
> 
> I've cleaned the tape and retried multiple times, to no avail.
> 
> I've tried omitting the directory containing the bad block,
> but that hasn't prevented it from terminating.
> 
> Anyone know a way to get around this?
> 

Untar from the non-rewinding device.  When it hits the bad spot
and aborts, just rerun tar again - it will start up the tape and
forward it looking for the end of file mark that signifies the
end of the current file and the beginning of the next.  You may need to
rerun it a couple times to get past the bad section.  You can also use
the "mt fsf" command to bump it forward.

Ted