We are looking into better backup solutions, including online backup, for our organization. Mozy offers an online backup service, and I use it for my laptop. At work we are currently evaluating a solution from Barracuda. You buy their hardware appliance and install it at your site. Their software backs up your servers to the appliance. Then at night the appliance transfers the data to their data center. Their software has a great user interface. You can throttle the bandwidth usage by time of day. It understands SQL Server and Exchange backups. You can even restore one deleted email. In a lot of respects, it looks great.
Online backup is oh so seductive, but there are two big gotchas.
1) It can take a LONG time to get your data up into the cloud -- weeks, or months, depending on the amount of data, and your pipe to the Internet. Once the original upload is done, then good backup software will just copy up what's changed, nightly. So theoretically it should work. But what if so much gets changed during the day that you can't shove it up to the cloud overnight? I would like all data to be located off-site every night, in case of a fire or something.
2) If your place burns to the ground, how quickly can you get your data back from the cloud? It may take a month to download it, again depending on the amount of data and your bandwidth. Barracuda and Mozy both say they will copy your data onto some kind of media and ship it to you. They are vague on how quickly they will get this to you.
Although our evaluation with Barracuda isn't quite over, my hunch is we will return our evaluation unit and invest in LTO4 tape. We found a local courier service that will come by every day and pick up our latest backup tape and return the older one for less than $400 per month.
By the way, Iron Mountain also offers courier services, and a very sophisticated online backup solution. Both services were a lot more money than we could afford.