Re: [gentoo-user] what isn't required to boot a system/what can be trimmed from a backup

[forgottenwizard <phrexianreaper@hushmail.com>]

On 11:18 Thu 13 Mar     , Iain Buchanan wrote:
> 
> On Tue, 2008-03-11 at 23:10 -0500, forgottenwizard wrote:
> 
> define "unneeded".  This is highly system dependant, as everyone puts
> important files all over the place.
> 
Things I would lose if I backed them up. Doing a prior backup, some
files in /proc caused me problems, and rsync refused to delete anything
in the following pass.
> 
> from the subject line I assume you want to be able to restore a bootable
> system?  If so, you may need to back up more than just filesystems.
> What about the partition table and the master boot record?  You can back
> up the mbr to a file by using dd:
>  $ sudo dd if=/dev/hda of=mbr.img bs=512 count=1
> (replace hda with your boot drive).
>
The table, mbr, and partition table I'm not worried about. Those can be
easily repaired (or replaced, depending on how one wants to do it)

> In terms of Gentoo, you can strip out /var/tmp /usr/portage /home and
> possibly /opt.  Probably some /var subdirs too like /var/log /var/www
> etc and some /usr subdirs like /usr/games /usr/include /usr/src etc.
> 
> I'd say you _need_ /dev /proc and /sys.
I'd like to know why. Some of the files in /proc change often, and cause
rsync a problem. sys doesn't cause these problems, though.
> 
> If you _really_ want to know for sure, turn on the atimes option in
> fstab for all your partions, then reboot and do a bit of stuff (log in,
> ssh, etc).  Then use `find` to find all files that were accessed.
> Something like this:
> 
>       * edit /etc/fstab, delete noatime (replacing it with "defaults" if
>         no other options remain)
>       * $ touch /var/tmp/reference
>       * $ shutdown -r now
>       * log in, look around
>       * find / -anewer /var/tmp/reference
> 
> The output from the last command will be everything you _need_ to boot.
> 
> Ideally, when backing up /proc /dev and /sys, do so from a cleanly
> shut-down system.
> 
> HTH,

I'm trying to do this with the system booted up, because doing a daily
sync like that would be a bit of a pain.

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