Date: Fri, 16 Oct 2009 17:37:32 -0400 From: Jerry McAllister <jerrymc@msu.edu> To: Stevan Tiefert <stevan-tiefert@kabelmail.de> Cc: freebsd-questions@freebsd.org Subject: Re: small question about tape-based dumps Message-ID: <20091016213732.GA61433@gizmo.acns.msu.edu> In-Reply-To: <1255727601.4640.4.camel@x1-6-00-11-09-00-e4-00.search.b.superkabel.de> References: <1255727601.4640.4.camel@x1-6-00-11-09-00-e4-00.search.b.superkabel.de>
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On Fri, Oct 16, 2009 at 11:13:21PM +0200, Stevan Tiefert wrote:
> Hello list,
>
> one example: If I have three partitions and I want to backup every day
> these partitions, will I need 21 tapes?
>
> I ask because it seems it is not possible to place more than one dump on
> one tape, isn't it?
You can easily put more than one dump on a tape if there is
room enough for them. Check out the mt(1) command.
Something like mt fsf 1 will skip over the first dump file
so you can write the second. mt fsf 2 will skip over two files, etc.
That is dump files, not files within the dump. Each dump of a
filesystem is one file.
If you need to restore, it is just the same. The first dump is
the first file. The second dump is reached by skipping 1 file
with the mt command, etc.
I actually rewind and skip between each dump of multiples made
to the same tape. I also use the no-rewind device for the tape.
So first dump is: dump 0af /dev/nsa0 /
For second dump: mt -f /dev/nsa0 rewind
mt -f /dev/nsa0 fsf 1
dump 0af /dev/nsa0 /usr
third mt -f /dev/nsa0 rewind
mt -f /dev/nsa0 fsf 2
dump 0af /dev/nsa0 /var
etc.
when all done mt -f /dev/nsa0 rewind
mt -f /dev/nsa0 offline
I have this all in a script that also writes an index file
as the first file on the tape.
Of course if you are doing a change dump the dump command is
going to look more like:
dump 1af /dev/nsa0
etc.
////jerry
>
> With regards
> Stevan Tiefert
>
>
>
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