Ubuntu – Restore backup with Rsnapshot

I'm a big fan of snapshots for backups, but I typically use them in the manner you'll find described for LVM snapshots -- Make a snapshot, mount it somewhere, back up the snapshot with your favorite backup tool (I like Bacula), then get rid of the LVM snapshot. Ideally this backup goes somewhere off-site

This dovetails very well with rsnapshot: Your rsnapshot snapshots can be instantly-available local backups, and they can also be captured in the off-site backup of the filesystem that you make from the LVM snapshot.

LVM snapshots are very similar to BSD UFS/FFS snapshots in that they store the deltas between when the snapshot was taken and the current system state: This means that performance will degrade as the snapshot and the main disk grow further out of sync, and there's some overhead for each snapshot you're maintaining (any change to the disk has to be tracked so the snapshot knows about it).
In practice this overhead isn't significant unless your disk changes frequently and you're keeping snapshots around for a long time.

See http://tldp.org/HOWTO/LVM-HOWTO/snapshots_backup.html for more on using LVM snapshots for backups (painted with the same broad strokes as what I just said).

Incidentally LVM (or UFS) snapshots are also a great "save game" kind of thing if you're about to do something REALLY DANGEROUS to a production server, but that's well outside the scope of your question

Ensure you are also monitoring your filesystem free space, monitor system logs for critical / severe messages, SMART output for your disks, network and backup services (ssh / rsync).

Regarding verifying your backups, you may want to setup your webapps environment in parallel and recover your backup periodically. Your backups are as good as your recovery.