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Date:      Sun, 7 Jul 2002 14:24:02 +0930
From:      "Rob" <listone@deathbeforedecaf.net>
To:        "Doug Hardie" <bc979@lafn.org>
Cc:        <freebsd-questions@FreeBSD.ORG>
Subject:   Re: Backups to CD-R - problems with filesystems
Message-ID:  <000601c22572$50fd4430$a4b826cb@goo>
References:  <000e01c22501$26e349e0$a4b826cb@goo> <f05111b1db94ce9ad8407@[10.0.1.90]>

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On 7 July 2002, Doug Hardie wrote:

> At 0053 +0930 7/7/02, Rob wrote:
> >I've had a few adventures in recent days trying to make CD-R backups. In
> >case I've gone down a complete dead-end, here's the objective:
> >
> >* Copy selected directory trees from 3 FreeBSD systems onto CD as a
> >   mountable filesystem (not a monolithic archive)
> >
> >The first challenge was to get the files onto 1 machine (with a CD burner).
> >I tried piping tar through ssh
> >
> >   goo# ssh gir 'cd / ; tar -cf - boot etc home usr/local/etc' |
> >        ( cd gir && tar -xpf - )
> >
> >but discovered that it misbehaves when the users in a tarfile don't exist
> >on the destination machine. Instead of leaving the files with numeric
> >owners, it chowns them to the user performing the extraction.
> 
> Having encountered the same problems, here is what I ended up doing. 
> Tar has the original V7 format available.  There is an option to 
> create in that format.  It does not use user names, but uses the 
> numeric uids and groups.  This will keep them constant for you. 
> However, it does not backup directories or their permissions.  Only 
> the files are written to the tar file.  When the extraction is done, 
> it will create any needed directories with the right names and 
> contents.  However the owner of the directories created will be that 
> of the user running tar.
> 
> What I am doing is creating the tar file on the remote machine using 
> rmt (e.g., tar -cv machine:directory/name ...).  That creates the tar 
> file on the remote server.  I archive tar files rather than the 
> originals.  I find it easier to restore from tar.   The command I use 
> to create the ISO image is:
> 
> mkisofs -R -J -V $DATE -o /backups/ISO/production.iso /backups/*.tar
> 
> I then ftp the iso image over to a Mac and burn a DVD.  The DVD then 
> mounts fine on FreeBSD and the tar files are directly accessible.  My 
> backups use about 95% of the DVD.  I have done some small backups to 
> CD and that also worked fine.
> -- 
> -- Doug
> 

Thanks Doug. I tried V7 format with tar, and found it didn't always 'do
the right thing' with directories. From memory:

* create a directory /home/fred owned by user fred
* archive /home in V7 format
* extract /home on another system
* tar restores the ownerships for /home/fred correctly
* but also sets /home as owned by fred!

This might not be the exact steps (it was a few days ago) but I was
certainly surprised by the results. Since I'm backing up /home as well
as other things, it's important to get the directories right.

Why do you prefer to put archives on the backup rather than the actual
files & directories?


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