Backup solutions (was Re: [Box-Admins] Permissions)

Göran Krampe goran at krampe.se
Mon Feb 7 00:26:38 UTC 2011


Hi all!

Been investigating this part and it seems to me that the three most 
interesting and mature tools for this is rdiff-backup, rsnapshot and 
duplicity.


Rsnapshot
=========
Rsnapshot is what we have used so far. It is a bit tricky to configure 
IMHO and I must say slightly confusing with the "backup levels". It 
needs a working rsnapshot on the destination, and since it uses hard 
links to create the illusion of "full snapshots" it will consume much 
more space if we have common changes to large files, like say Squeak 
images - or hey, even worse, VirtualBox/VMWare images :) It also has 
issues with "file selection quirks" based in oddities in rsync - like 
sensitivity to trailing slashes etc.

Rdiff-backup
============
Also relies on being on destination like rsnapshot. Saves metadata 
separately from the mirror, does not use hardlinks but instead maintain 
the mirror and store the increments from older snapshots on the side. 
Some report it is rather slow. Does not have "file selection quirks" but 
does also not have "backup levels". Seems simpler to use though. Cosumes 
less space on destination since it does not rely on hard links. Can be 
used with archs (http://code.google.com/p/archfs/) to create a FUSE 
illusion of full snapshots like rsnapshot has.

Duplicity
=========
Does NOT rely on being installed on destination, thus can use "dumb 
servers" through scp/ftp etc. Does NOT maintain a mirror on destination, 
but instead keeps file data in compressed tar files typically taking 
less space than rsnapshot/rdiff-backup. Can use encryption, which the 
above tools do not. Very simple to use and understand, although restores 
are of course not just an "scp yadda". Speed should IMHO be good 
compared to rsnap/rdiff since it keeps signatures etc on source and 
should not need to do ANY round tripping - not verified though, we would 
need to test.



I picked Duplicity because I wanted to use an external USB drive with 
vfat on it as destination, and Duplicity splits very large files so can 
easily backup my VirtualBox 12Gb files onto it, which of course 
rdiff-backup failed.


Conclusion
==========
If we want people to give us a bit of their harddrives for nightly run 
backups it seems to me that Duplicity might fit the bill best:

- Smaller size on destination (compressed)
- Does not need duplicity on destination, just a dumb server
- Good speed (we would need to test and compare)
- We could use encryption to make it less "scary" to replicate stuff 
like "/etc" to boxes not under our direct control.

It does not handle hard links though, but perhaps not a big issue for us?

regards, Göran


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