Tuesday, September 23, 2014

Mac OS X time machine backups to a windows or linux samba share

Time machine is a great product from Apple. I used it just recently when I replaced my laptop. All I had to do was select the time machine disk when booting up for the first time and everything was just how I left it. Fantastic!

Creating backups is now very important to me. With a USB hard drive this is very simple, but I wanted to take backups to my home server, where there is plenty of secure space.

Making a backup to network drives (like windows and linux samba shares) is not supported out of the box. I'll show you how to do it.

Setting up the network drive

This guide assumes you have a network-attached drive that's available and mounted. You can use samba to create this drive on either windows or linux.

Creating the sparse disk

A sparse image is an image that grows in size. It's a mac thing. This image will become our dmg file that gets mounted.

Open up up the disk utility. You can do this by searching for it in finder:

  • Give it a name with something you'll remember
  • Before you do anything else, change the image format to "sparse disk image". This will allow us to create a 300GB disk image without allocating all of that space at once.
  • For format select "Mac OS extended"
  • For size select "custom" and put in your desired size. The image will grow to this size.
  • For partition select "single partition -- apple partition map"
  • Save it to your network network mount

You'll see that the disk is 300GB (or whatever size) large but you're only using around 300MB of it.

Next we need to run a command that will force time machine to use our new disk. Find the mount point for the disk. If you select the disk in disk utilities, you can find it at the bottom. In my case it's "/Volumes/stephen_time"

Open up your terminal and paste in the following command:

sudo tmutil setdestination <mount point>

Now open up your time machine preferences and check out the new disk:

Hurray! You've got your disk loaded and ready to use. Now just do the backups as normal. You'll need to remount the disk (find it and double click it) when you want to make backups.

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