Backup Time Machine to Non-Native Drives & Network Attached Storage
Using the command line in OS X, you can enable a hidden feature in Time Machine that allows you to backup your Mac to a non-native volume, including Networked Attached Storage devices, network volumes, or even a Windows PC. This is generally best for advanced Mac users, as it must be enabled through a defaults command string, let’s walk through it.
Warning: this is an unsupported feature in Mac OS X and Time Machine, relying on this method to backup your data could be risky. Proceed at your own risk.
How to Enable Network Drive Support in Time Machine for OS X
To get non-native drive support, launch the Terminal and enter the following command:
sudo defaults write com.apple.systempreferences TMShowUnsupportedNetworkVolumes 1
Now you’ll be able to access non-native NAS volumes through Time Machine setup.
Don’t forget that this is an unsupported feature in Time Machine which is why it isn’t enabled by default, relying on this for your backups may not be the best idea. Apple probably chose to keep it unsupported for several reasons, but remember there’s always a potential for packet loss with network traffic, particularly wireless networks. Packet loss in the case of a backup could result in corrupted or missing data, so if you plan on using this feature you may want to stay on a wired ethernet network to reduce the chances of any transmission loss.
I tried this briefly and got the “Time Machine backup delayed” message, forcing a manual backup to resolve the error. It’s my strong recommendation that you’ll just backup Time Machine to a dedicated backup drive that is physically connected to your Mac, this is without a doubt the most reliable method. Nonetheless, if you’re in a pinch, it’s nice to know you can bend the rules if a situation requires it.
If you want to disable the Time Machine network volume support feature, you can do so with the following defaults command:
sudo defaults write com.apple.systempreferences TMShowUnsupportedNetworkVolumes 0
Thanks to Nick for sending this in!