Backup to CD-Rs and DVDs.

Julien Gabel jpeg at
Sat Jan 29 06:32:15 PST 2005

>>> I'm in the same boat as Xian.  I want to backup to DVD so I can
>>> upgrade to 5.3.  dump in 4.10 does not have a -P option, and growisofs
>>> says nothing about handling spanning, so how do I span my dump over
>>> multiple DVDs?
>>> Then some day if all goes well I will split /usr into /usr and
>>> /usr/home, 'cause this is ridiculous.

There is 2 limitations here:
  - The dump's option '-P' is relatively new, and not supported on old
  - A file can't be larger than 2Gb using an ISO 9660 file system.

Knowing these 2 points here, here is a sh(1) shell script than i use
and which do the following:
  1/ Backup a remote FreeBSD system on a local DVD writer;
  2/ Currently 5.X since i hardcoded the dump's option '-L') but that
     is easily bypassed;
  3/ Over ssh;
  4/ Using a remote user which must be in the group 'operator';
  5/ Because i use the same grown iso fs to hold all the backuped fs,
     this script need a local temporary space which size just need to
     be the size of the larger compressed remote fs (generally /usr
     or /home) not a sum of all of these;
  6/ Automatically get the fs to backup from the remote fstab (begining
     with the root fs).

As it is a little _home_script_, there is some caveats to know:
  - It must launch as root from the local system in order to be able
    to write to the local DVD burner;
  - It assume that that the larger compressed remote fs is lesser than
    the 2Gb limitation (you can for example set the nodump flag on
    /usr/ports/distfiles/*, if this is not an issue for you, to decrease
    the size of the /usr dump);
  - Some commands/options are hardcoded;
  - May be extended to managed more than one copy of each backuped fs
    if there is sufficiently space left on the DVD...

Oh, yes... to restore just do the following (/home for example):
  # mount -t cd9660 /dev/cd0 /cdrom
  # cd /home; gzip -dc /cdrom/home/dump.gz | restore -ivf -

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