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So by now you may be aware that Apple only supports Time Machine on internal, directly connected or volumes shared wirelessly via AirPort, right? Why not regular Network Attached Storage (NAS) volumes? Because they’re unsupported at this time. So let’s run with that risk here and experiment with using an unsupported NAS volume.

First my back story: I previously backed up to the cloud using Haystack Software’s Arq to Amazon Web Services (AWS) Simple Site Storage (S3). What I most liked about it was that the backup was off site and that it kept versions over time much like Time Machine does. Off site means that I’m less likely to lose my backup in the same incident whereby I lose my primary set of data (e.g. theft, fire, flood, accident, whatever). What I do not like about backing up to the cloud is the time it takes to back up, especially at the outset and whenever you do some major re-org on your disk. Conversely, the time to recover individual files may be slow but acceptable — but waiting days to recover all or many of your files from the cloud is unacceptable, even though it’s a fact of life. Downloading a 250Gb file takes time. Then there’s the cost (albeit minimal for both Arq, one time, and AWS’s S3, monthly) — when you may already have access to a free NAS volume at no additional cost.

WARNING: This blog post is an experimental journal, the results are not yet in. In addition to testing whether I can write successfully over time to an unsupported NAS volume, equally important will be to recover not just individual files but my whole drive from the backup. At this point I have merely identified how to direct Time Machine to an unsupported NAS volume. I haven’t written to it yet. I’m waiting on a separate test volume to do that — so that my work doesn’t impede on production (in terms of performance, space used etc.). Please add your own experiences in the comments, they will be much appreciated. I’ll add to this blog as the experiment progresses.

I’m experimenting with a MacBook Air under Mac OS 10.6.6 and Time Machine 1.1



In your NAS volume, create a folder structure that will be the path to your Time Machine backups. Eject the volume and now mount only the share point into which Time Machine should write its files.

e.g. the difference between …
smb:// and
smb:// (the path to your Time Machine share point)

As an administrator, launch Terminal and enter this single line of unbroken code to enable access to unsupported volumes in Time Machine …
defaults write TMShowUnsupportedNetworkVolumes 1

Launch Time Machine (I did not have to reboot), “Select Backup Disk” now the previously unavailable/unsupported volumes will appear. Select the share point you’ve created for Time Machine and punch “Use for Backup”. Authenticate with username and password if challenged. Time Machine is now enabled and will start backing up within seconds. Here’s the sequence in pictures (including reversing out) …

To disable using NAS:
1. Open Time Machine preferences. “Select Backup Disk”, select “None” from the list of volumes and then “Stop Backing Up”.
2. Launch Terminal and enter this single line of unbroken code to disable access to unsupported volumes in Time Machine …
defaults write TMShowUnsupportedNetworkVolumes 0


Suggested Links: Wikipedia’s entry on Network Attached Storage (NAS) | Haystack Software | Apple’s Time Machine


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