The relentless commercials for remote backup almost had me convinced to retire my arcane system of external usb drives and cases of DVDs on my bookshelf. Then a couple of weeks ago that little bit of doubt I was feeling became a reality for users of the T-Mobile Sidekick when a server failure at Microsoft’s Danger division left them holding a dataless hunk of plastic. Sidekicks rely on the servers at Danger to store things like contacts, photographs, notes, to-do-lists and other important user data. Sidekick users could do little but wait for Microsoft to restore the data. The interruption was so bad that T-Mobile temporarily stopped selling Sidekicks.