[Techtalk] Prodigal daughter and dual boot woes

[Kathryn Andersen]

On Thu, Apr 16, 2009 at 10:11:20PM -0700, Amanda Haynes wrote:
> Thoughts?  Ideas on how to automate my backups?  I'm sure there's some
> software out there that will do it for me :)  Good virtualization software?

My current backup solution is an external USB drive, and rsnapshot run
8-hourly, daily, weekly and monthly with a cron job.

What rsnapshot does is take a "snapshot" of the directories you tell it
to back up, but it uses hard links to save space for files that haven't
changed since the last snapshot.  This gives a number of advantages:
a) all backup snapshots are immediately accessible, since they are
copies, not tarballs or some other application-specific backup format.
b) one still gets versioned backups
c) it doesn't take up as much space as a naive copy would.

Of course, it helps that the external USB drive is much bigger than the
actual hard drive it is backing up.

I don't actually back up the entire hard drive, just a subset of it;
everything in /home, /etc, /usr/local, /var/spool/cron, /var/www,
/var/log, /root and /boot/grub.  I would do /var/spool/mail too, except
that I use Maildirs in people's home directories, so that's covered by
the backup of /home.  That set of directories gives me a copy of the
stuff that is irreplaceable, such as configurations and mail and
personal stuff.  The rest can be recovered by doing a re-install, so I
don't feel the need to back it up.  It's one of those time/space
trade-offs: I save space by not backing up everything, at the cost of
the extra time required to recover from drive failure.

And speaking of drive failure, I also have a backup-backup, in case the
external backup drive fails.  Which I instituted after that very thing
happened.

My backup backup is *another* USB drive which has a nightly rsync copy
of my desired directories.  This one is a smaller drive than the big
backup one, hence the naive copy.  But that still gives me one (day old)
copy of my important files.

Backing up to a separate drive with a cron job is the only way I've
managed to ensure that I had *regular* backups.  Backing up to removable
media such as DVDs is no good, because a single DVD isn't going to
contain all the things I want to back up, and once it gets larger than a
single DVD, then it has to be done manually, and anything which has to
be done manually isn't going to be done regularly enough.  That's just
human nature.

Kathryn Andersen
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