Date: Fri, 16 Oct 2009 20:43:26 -0600 From: Tim Judd <tajudd@gmail.com> To: Jerry McAllister <jerrymc@msu.edu> Cc: freebsd-questions@freebsd.org Subject: Re: small question about tape-based dumps Message-ID: <ade45ae90910161943o7695d436wed8b8a69d92ef994@mail.gmail.com> In-Reply-To: <20091016213732.GA61433@gizmo.acns.msu.edu> References: <1255727601.4640.4.camel@x1-6-00-11-09-00-e4-00.search.b.superkabel.de> <20091016213732.GA61433@gizmo.acns.msu.edu>
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Replies inline On 10/16/09, Jerry McAllister <jerrymc@msu.edu> wrote: > 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 / I understand that this creates a dumpfile on nsa0, and as I understand tapes (which may be wrong, which I ask for clarification here).. To mark a end-of-file to be able to fast-forward/rewind, why can't you use: mt -f /dev/nsa0 weof It's description in mt(1) says it writes the end-of-file mark at current position > For second dump: mt -f /dev/nsa0 rewind > mt -f /dev/nsa0 fsf 1 > dump 0af /dev/nsa0 /usr So if we use weof, would the 2nd dump then be: dump 0af /dev/nsa0 /usr mt -f /dev/nsa0 weof > third mt -f /dev/nsa0 rewind > mt -f /dev/nsa0 fsf 2 > dump 0af /dev/nsa0 /var And 3rd: dump 0af /dev/nsa0 /var mt -f /dev/nsa0 weof > etc. > > when all done mt -f /dev/nsa0 rewind > mt -f /dev/nsa0 offline And I've never used offline, guess I'll start now. > 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 Thanks for any input! --TJ
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