May 03, '10 07:30:00AM • Contributed by: mike666
I have a good sized ZFS volume on my desktop machine which I'd like to use for Time Machine backups for all my systems. This is no problem with backing up my other systems over the network thanks to this command:
defaults write com.apple.systempreferences TMShowUnsupportedNetworkVolumes 1Works like a champ backing up my portable to that volume shared over AFP. But I also wanted to keep the boot drive on the desktop machine backed up to that same volume, which turns out to be almost unfeasible until Apple decides to let us use Time Machine with the mounted HFS+ disk image of our choice.
Apple also doesn't let you mount AFP or SMB shares on the machine you're sharing from, so that wasn't an option either (they should, though -- it would be great for testing purposes, as well as something like this).
I did a lot of research and only came up with one solution. It's not ideal, but it appears to work. Please don't bug me about ZFS's better uses and more advanced features; ZFS is unsupported and may break at any moment, so I'm just using it to provide some fault tolerance for seven 250GB drives. Also be aware that my desktop machine is a G5, and therefore is limited to OS 10.5.8.
Basically, the solution is pretty simple but requires an internet gateway or router which doesn't filter NAT redirects. Just share the volume you want to use, and then open up port forwarding on the gateway for AFP (port 548) to the IP of the machine you're sharing from.
Connect to afp://yourWANIP/yourShareNAME (get your WAN address, if necessary) from that same machine, and then select it in the Time Machine destination prefs. Run the defaults command above if it doesn't show up.
Because of the latency of gateway devices, it is super-slow but it does work. Of course, security, blah blah blah: make sure you don't have an easy-to-hack usernames or passwords on your system. If need be, add a second gateway behind your internet gateway if you're really worried.
I had looked into doing an NFS share, re-mounted locally so I would only have to go through my local NIC, but I couldn't get that to show up in Time Machine's destination list. If someone else has a proven method which doesn't involve the network, I'd love to hear it.
[robg adds: I haven't tested this one.]
