Re: [gentoo-user] How to build a time machine on Gentoo

[Alex Schuster <wonko@wonkology.org>]

Nganon <nganon+gentoo@gmail.com> writes:

> Hello all,
> 
> My first post on the list. I thought I would start with something
> that I started
> to think of as 'essential' after losing 90GB of data. Now I have two
> main questions in mind: what to and how to back up on gentoo most
> efficiently.
> 
> 1. Apart from users' home directories and the followings, what should
> be backed
> up on a gentoo machine?
> /etc/portage/
> /root
> /var/lib/portage
> ...?

Wouldn't it be easier to just backup the whole / directory?
Excluding /home, /usr/portage and /var/tmp/portage?


> 2. Erm..okay, I am gonna say, what magic I want and then ask your way.
> I first started making gzipped tar balls as follows:
> 
> tar czpf /media/backups/userA-`date +%Y.%m.%d`.tgz -X
> userA-excludelist /etc
> 
> But these can get huge especially for home dirs. I also want safe dvd
> copies.
> Though I can find enough space on the external drives, I don't trust
> them any more. See above..sigh..(No I recovered about one third of it
> with testdisk/photorec
> which names them as file000001 file00002.. and half them are zero
> sized.. which
> quite justifies my agony)

Okay, but I don't trust DVDs. Although DVD-RAM is quite safe I heard.
But external disks are flexible, offer more space, and if you want more
security, just use yet another drive, so you are safe even if your main
drive and a backup drive fails.

I suggest you have a look at rdiff-backup. It gives you a 1:1 copy of
the source directory, but also does incremental backups, which are
stored (in compressed form) in an additional folder in the destination
directory. I would use this at least for things like /etc, where I
sometimes might want to retrieve an old version of a file. Similar to
your approach with big tar files and small ones containing the
increments.

I use a script for my backups, which I mentioned here on 2010-05-07,
subject 'Snackup'. It optionally creates LVM snapshots so I can make
backups from the running system, even if the source directory is
altered during the backup. This works on LVM only, though, and also
allows the volume to be LUKS-encrypted. It does backups by rdiff-backup,
rsync, cp, tar or dd. It may be overkill when not using the LVM
features, but still I suggest to use some script for backups, so one
does not always have to remember the backup commands. When I want to
update my backup, I enter something like 'snackup boot root home src',
and the script backs up my boot, root and home partition in the
background, and creates tar files each directory in /usr/src.


> By the way, since I want dvd backups as well, and I want to use +rw
> dvds so I can overwrite old backup after a while, what is best way of
> ensuring the integrity and safety of them. Is it a good idea to use
> truecrypt containers? Or nothing tops signing and encrypting with gpg?

I'd use DVD-RAM. The media is a little more expensive, but AFAIK they
were made with long-time backups in mind. And access is much easier,
you just copy the files as to an external drive, no need to burn ISOs.

	Wonko