I've been running TimeMachine over SMB to a Linux host for a couple of weeks but it's not for the casual geek. The details for those who want it:

1) I'm doing it over a gigabit ethernet cable. It would suck over 100mbit, and would be terrible over 10mbit or wifi so I wouldn't even attempt it unless you've got some cable for at least the initial sync.

2) Since time machine likes to be the main player on a particular drive/mount, I set up a new samba share specifically targeted to a TimeMachine directory. That way I can mount it from Finder and it looks like a happy, empty drive. Now the trick- touch a file in the root of that mount called .com.apple.timemachine.supported - this will override Time Machine's reluctance to use a network drive. As soon as you do that, it'll be a drive option in the preference pane for time machine.

3) Once you've got that started the first time, Time Machine asks you for the network mount password so it can reconnect on demand for making incremental backups. Restoring is trickier than off a regular drive, but not impossible. The trick is that you need to mount that SMB share, and then mount the diskbundle stored on that share, BEFORE you run TimeMachine.app. It'll prompt you when you start it up to select an old backup source- basically you just have to confirm that you want it to use that image you've mounted.


It's plain to see why Apple just killed network backups out of the final release since use over a network has a lot of rough spots, but if you're UNIX savvy and want to make it work, it's certainly possible.

p.s. An added bonus is that SMB respects filesystem quotas... so if you create a timemachine user and assign it a disk quota, you can effectively cap TimeMachine as you see fit and prevent it from consuming an entire disk.

Like I mentioned,

the "touch .com.apple.timemachine.supported" no longer works in the Retail build of Leopard.

Sorry for breaking it to you, it was a nicely written post, but alas, it will not work for anyone.