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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