Time Machine over AirPort ExtremeA couple of months ago when Apple finally (and quietly) enabled the feature in Mac OS X that allowed hard drives connected to AirPort Extreme base stations to behave the same way as Time Capsule volumes, i.e., allowed them to be used for Time Machine backups, they insisted that this was an "unsupported feature". Being the owner of such a set up, in my excitement of being able to have wireless backups, I blatantly ignored aforementioned warning and went ahead and set up Time Machine to use that drive for backups.
And everything was blue skies and sunshine until yesterday arrived.
That was when I started getting "Time Machine Backup Failure" messages and after a few of these (including some that ironically told me that my backup disk was failing and I should back it up), I disconnected the backup drive from the AirPort Extreme and plugged it in directly to my Mac. Apparently, the disk image inside the backup volume had become disastrously corrupted, which meant that even multiple sessions of Disk Utility weren't able to repair it, and in the end, deciding that trying to repair the backup disk image was not worth my time, I just erased the disk. I'm going to use it over USB from now on.
Bottom Line: When they say "unsupported", they mean "unsupported", so don't use Time Machine with disks connected to AirPort Extreme base stations. However, I do have to say that if it's "unsupported", why is it exposed in the UI in the first place?