Re: lenny backups and recovery
On Fri, 15 Jan 2010, Paul E Condon wrote:
Contrary to tldp advice, I think it is unnecessary to make backups
of /bin or /sbin. These files are readily available from you favorite
I'm very much a fan of backing up the entire system (with limited
exceptions, such as an area set aside for the storage of downloads, that
is not backed up.
The problem is that unless you restore to the _same_ binary you can't
guarantee the same behaviour. This is essential in the case of server
backups where there is little tolerance for behavioural changes but still
applies to desktop systems.
A similar argument applies to the complete setup of the system. Despite
the best change management, small and non-obvious changes can occur in a
system. If you reinstall from the repo and restore the config from /etc
you may still be missing something (eg, a symlink) and find an app is
broken when it was previously working. Backing up the entire state of the
system means that when you do a DR you get back a known working copy of
the system, since it was working before.
I'd consider having to reinstall from original media a failure of the DR
system.
When I first started with Linux the system (binaries and config) took up
about 80% of the disk. Now it takes up less than 2%, so backing up the
system components hardly adds any pressure to the backup system. It also
allows for a much faster recovery following a DR.
Also, important data has a way of hiding in more places on the disk that
you think it will. If you start excluding parts of your system from the
backups you increase the liklihood of missing something important in the
backups.
This is covered in more detail in my backup talk notes (which I did
mention earlier in the thread):
http://www.timetraveller.org/talks/backup_talk.pdf
Debian repository, and if your system has crashed in some serious
way, you would be well advised to download again, once you think you
have resolved the issue that caused the crash. Think about it ---
if you have to restore one of these, something really bad has happened
and you can't be sure that something -else- bad hasn't also happened -
but you haven't noticed it - yet.
That's where testing of the backup system comes in. You never know that
DR will work unless you test it.
Cheers,
Rob
--
Email: robert@timetraveller.org
IRC: Solver
Web: http://www.practicalsysadmin.com
I tried to change the world but they had a no-return policy
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