[rdiff-backup-users] Re: First restore gone horribly wrong

[Trevor Cordes]

On Fri, 17 Sep 2004 chris young <address@hidden> wrote:
> When the techs left me the re-imaged drive the operating system was the 
> same version as I had in my backups but MySQL was not. I thought I could 
> just restore everything I had backed up, overwriting the older versions 
> of software, and end up with the system back where I started from.

I've been using rdiff-backup for a couple of years at many sites and it 
works great.  I do not and probably would not use it as a "system file" 
backup system.  I do/would use it only for data.

There are a number of problems with using it for system file backup.  The 
first is the UID issue you describe.  Even with mapping, that's adding a 
layer of complexity to the issue I'm not sure I'd feel comfortable with.

The second problem is directories you are excluding (dev, proc, etc).  If
your tech restores you to an old image of the drive, and you restore from
a rdiff-backup backup, then those directories might not be up to date. 
What I mean is you may have (I hope!) updated/patched/removed/installed
packages between the original image date and the restore date.  Those 
package changes may affect (add, remove, alter) files in those excluded 
directories.  So if you restore from an image and then restore from 
rdiff-backup, you'll have a confused and messed up system where some files 
in those directories are out of synch (ie: older) with the versions the 
system thinks are installed.  Unpredictable results will follow.

A Linux install is so easy to rebuild from scratch (compared to Windows
Server!!) that all you really need to do is backup /etc, /var and anything
in /usr/local.  When you have to restore, just put back in the rpm's you 
need and copy back in the appropriate config files.

In fact, I use a script to automatically build linux boxes to my spec 
after a minimum (no-package selected) install.

For better "system" backups, I'd look at RAID (like cheap IDE RAID 1 
devices like ARAID, Duplidisk or Stardom).  The ARAID and Stardom are neat 
in that they clone to a disk on the fly (hotswap!) and you can then take 
that extra disk offsite and put the mirror disk back in.  All this without 
ever taking the system offline!

If you're off-site, I'm not sure what the best way to do a full "system" 
backup would be.  It's a tough problem.