I am having trouble finding a backup strategy for our code assets that 'just works' without any manual intervention.

Goal is to have an off-site backup (a synchronized one) so that when we check-in files, create builds, etc. to the network drive, the entire folder structure is automatically synchronized and backed-up (in real time, or 1x per day) at some off-site location so if our office blows up, we don't lose all of our data.

I have looked into some online backup services, but have not yet had any success. Some are quirky/buggy, others limit file size and/or kinds of files (which doesn't work well for developer files).

Everything gets checked in and saved to a single server (on a Raid Mirror), so we just need to have a folder on that server backed up/synchronized to some off-site location.

So my question is this. What are you using for your off-site backup strategy. What software, system, or service? Is there a be-all/end-all system of backing up your code assets that I just haven't found yet?

Thanks