Random tape backup goodies

[Commie Pinko Dirtbag]

One:
To position the tape after the end of the last valid file (so you don't overwrite things):

mt -f /dev/nst0 seod

If you want to make sure the tape head starts from a sane position but you don't want to do a full rewind before the above positioning, try this:

mt -f /dev/nst0 bsf 1 && mt -f /dev/nst0 seod

From that point on you can write the tape to your heart's content and you won't be overwriting any previous files on it.

Two:
Have you ever recorded a sequence of tarballs into tape and upon reading them find out there's a "null" tarball between each one and the next? Use the "i" flag so tar skips any block of zeros at the end of file:

tar xzivf /dev/nst0

That way the next tar will read the next file the way it should be.


(Your tape device may be in a different place than /dev/nst0. If so, change accordingly)

[Commie Pinko Dirtbag]

1. Small correction: the second command line won't work if...

...tape is already rewound. (rewinded?) Use this instead:

mt -f /dev/nst0 bsf 1 2>/dev/null ; mt -f /dev/nst0 seod