[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

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


Reply to: