I've been backing up my WP site (pin4todd.com) for a couple years. It does not change often, so I don't worry about it too much. I just returned from traveling and found all my backups for September failed.
In looking at my backup-technology.com account, I saw two entries for my blog, one for the old plugin version and one for the new. The entry for the old plugin was using 99% of my space, and the entry for the new plugin was using none. I'd updated the plugin at the beginning of the month, so my first reaction was that the new version wouldn't overwrite old backups, yet they were the same blog so I'd run out of space. I chose to delete the entire archive for the old plugin version since I have several full backups on my computer. It said I had a while to undo the delete.
Then I thought maybe I was overreacting, so I clicked on the link that says: Cancel deletion (scheduled for 11-09-2012 16.05.14)
And I got:
Oops! The page requested does not appear to exist.
I'm still digging through all the errors trying to figure out if maybe another plugin was conflicting, but I wanted to report this problem first.