Tips from the blog VIII: Time Machine on QNAP NAS

This is just a quick tip as it took me a little while to sort this out. In the lab we have two QNAP TS-869 Pro NAS devices. Each was set up with a single RAID6 storage pool and I ran them as a primary and replicant via rsync. We recently bought a bigger server and so the plan was to repurpose one of the NAS boxes to be a Time Machine for all the computers in the lab.

We have around 10 computers that use a Time Machine for small documents that reside on each computer (primary data is always on the server). So far, I’d relied on external Hard Drives to do this. However: 1) they fail, 2) they can get unplugged accidentally and fail to backup and 3) they take up space.

As always the solution is simple and I’ll outline this with the drawbacks and then describe the other things I did to save you wasting time.

  1. Wipe the NAS. I went for RAID5, rather than RAID6. I figured this is safe enough. The NAS emails me if there is a problem with any of the disks and they can be replaced.
  2. Enable Time Machine. In the QNAP interface in Backup Server>Time Machine, click Enable Time Machine support. Set a limit if you like or 0 for no limit. Add a Username and Password.
  3. Pick the NAS as the Time Machine disk. On each Mac, wait for backup to complete, turn Time Machine off. In Time Machine Preferences pick new disk. It will see your QNAP NAS Time Machine share. Click on it, enter user/pass. click OK. Don’t select use both disks (an option in Yosemite onwards).
  4. That’s it. Wait for backup to complete, check it. Unplug external HD and repurpose.

You don’t need each user to have a share or an account on the NAS. You don’t need to mount the volume on the Mac at startup. The steps above are all you need to do.

The major drawback is that all users share the same Time Machine space. In theory, one person could swamp the backup with their files and this will limit how far back all users can go in the Time Machine. The NAS is pretty big, so I think this will be OK. A rule for putting data/big files in a directory on a user’s Mac and then excluding this directory from the Backup seems the obvious workaround.

What not to try

There is a guide on the web (on the QNAP website!) which shows you how to add Time Machine support for a Mac. It requires some command line action and is pretty complicated. Don’t do it. My guess is that this was the original hack and this has now been superseded by the “official” support on the QNAP interface. I’m not sure why they haven’t taken this guide down. There is another page on the site, outlining the steps above. Just use that.

I read on the QNAP forums about the drawback of using the official Time Machine backup (i.e. all users having to share). My brainwave was to create a user for each Mac, enable a home folder, limit the account with a quota and then set the Mac to mount the volume on startup. This could then be the Time Machine and allow me to limit the size of the Time Machine backup on a per user basis. It didn’t work! Time Machine needs a specially formatted volume to work and so it cannot use a home folder in this way. Maybe there is a way to get this work – it would be a better solution – but I couldn’t manage it.

So there you go. If you have one of these devices. This is what worked for us.