Date: Mon, 17 Feb 1997 22:08:11 -0700 (MST) From: Wes Peters <softweyr@xmission.com> To: "Adam W. Hawks" <root@slip129-37-195-203.nc.us.ibm.net> Cc: questions@freebsd.org Subject: SCSI tape question Message-ID: <199702180508.WAA16991@obie.softweyr.ml.org> In-Reply-To: <199702180015.TAA06887@pent.ibm.net> References: <199702180015.TAA06887@pent.ibm.net>
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Adam W. Hawks writes:
> I have recently got hold of a EXABYTE 8200 and know how to save and retreive
> a single backup from the tape. I have 2 questions.
>
> (1) How do I save another backup on a tape that is not full along
> with the first without overwritting it?
There is an oddity in UNIX tape device drivers called 'no rewind'
devices. With a normal tape device, when you close the device after
using it, i.e. for a tar, cpio, or dump, the tape is rewound. The
no-rewind device leaves the tape where it is. This allows you to write
a second, third, etc. backup file on the same tape, starting where the
previous one left off.
The mt command allows you to manipulate the tape in the drive in several
ways, including skipping forward and backward over files. If, for
instance, you want to restore a tarball on the third file on a tape, you
could:
$ mt rewind
$ mt fsf 2
$ tar xvf /dev/nrst0
See man mt for more info.
> (2) How do see what and how many backups are on a tape? or am I out of luck
> unless I put a paper label on it.
If you consistently use one backup program, i.e. tar, you can dump the
contents of the tape by using the no-rewind device until you run out of
files:
$ mt rewind
$ tar tvf /dev/nrst0
$ tar tvf /dev/nrst0
$ tar tvf /dev/nrst0
...
--
"Where am I, and what am I doing in this handbasket?"
Wes Peters Softweyr LLC
http://www.xmission.com/~softweyr softweyr@xmission.com
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