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Date:      Fri, 23 Jan 2009 15:54:18 +0100
From:      cpghost <cpghost@cordula.ws>
To:        Gary Kline <kline@thought.org>
Cc:        freebsd-questions@freebsd.org
Subject:   Re: how to create a DVD backup filesystem?
Message-ID:  <20090123145418.GA1013@phenom.cordula.ws>
In-Reply-To: <20090123065949.GA96433@thought.org>
References:  <20090123011043.GA86638@thought.org> <20090123014001.GA2536@phenom.cordula.ws> <20090123065949.GA96433@thought.org>

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On Thu, Jan 22, 2009 at 10:59:49PM -0800, Gary Kline wrote:
> On Fri, Jan 23, 2009 at 02:40:01AM +0100, cpghost wrote:
> > Perhaps there is something like that, but I do it manually like this:
> > 
> > * mkdir cdr/
> > * copy approx 3.0 to 3.1 GB worth of files into cdr/
> 
> 	You mean, I'm guessing, my devel files/subsirs, Music files, and
> 	other text and data, correct?

Right. BTW, nothing prevents you from copying subdirs into cdr/ ;-)
Just make sure that you don't overfill cdr/:

* du -s -h cdr/

would give you the current size of everything in cdr and below.

> > * mkisofs -R -J -o cdr.iso cdr/

You can also use -r instead of -R, as it would fix the permissions
for you (see man mkisofs). Sorry for the omission.

> > To use growisofs, install it from /usr/ports/sysutils/dvd+rw-tools.
> > You may need to
> > 
> > # kldload atapicam
> > 
> > so that you can get /dev/cd0. Don't forget that you need write
> > permission to /dev/cd0 and /dev/pass0, so either run growisofs
> > as root, or add this to /etc/devfs.rules:
> > 
> > perm    cd0     0666
> > perm    pass0   0666
> > 
> > and restart devfs (/etc/rc.d/devfs restart).
> 
> 	I set this up at least *three* times.  ....

Wrong rule set? See "man devfs".

> > If you plan to archive the DVDs, be sure to schedule some date in
> > a couple of years ahead to read them back in and verify their
> > condition. If some of those DVDs developed bad sectors, you could
> > then try to reconstruct those with dvdisaster (but only if you created
> > the error correction data before burning!), and burn a new DVD.
> 
> 	I'm planning on burning a new DVD every few months; storing
> 	off-site.  Probably recycling some discs.

That's a good idea. As long as you check the DVD every couple of
years or so, and you have error correction codes available, you
should be safe. Oh, and do also save the dvdisaster distfile,
just in case. ;)

> > Oh, and try to stick to good DVD blanks like Taiyo Yuden or Verbatim
> > (only those made in Taiwan or Japan) to minimize the risk of bad
> > sectors (i.e. especially avoid no-names or el-cheapo blanks).
> > 
> > You can also do without dvdisaster, and write more than 3 GB to the
> > DVDs, but if you plan to archive them and be able to read them a few
> > years ahead, you'll highly value the error correction codes
> > overhead. ;) Oh, and you'll still have to read the data back after
> > burning, just to be sure everything's okay. Some kind of checksums
> > (md5, sha256) of the directories would be useful, so plan ahead
> > and add them before creating the ISO.
> 
> 	I'll have checksums Plus usin the dvdisaster, :-)  [[ i actually
> 	did this in the 90's with my floppies; when the CRC failed i knew 
> 	a floppy had gone south. ]]

Yup. Just remember that losing a couple of floppies is not the same
disaster as losing a couple of DVDs. ;-)

Regards,
-cpghost.

-- 
Cordula's Web. http://www.cordula.ws/



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