How To Disable Time Machine Local Backups (and Relinquish Space in the MobileBackups Folder)

This morning, after importing a bunch of RAW files from my Nikon camera, I was startled (once more) by the lack of responsiveness of my MacBook Pro running OS X Lion.

Since the update, in fact, I'm growing pretty disappointed with Lion. It never roared just like the good ole Snow Leopard. The Lion cub has only shyly purred and whined, so far.

One of the things that bothers me most is Spotlight performance. Assuming you noticed it, have you ever wondered what the mdworker process is doing when it jeopardizes your Mac resources? I have: staring impotently at the screen, listening to the spinning rust crackling, powerlessly witnessing how the operating system is waiting to complete who-knows-what.

This morning, I opened Lightroom, started importing some RAW files, and started working on them. Well, trying to work on them while Lion was performing its... "housekeeping".

Frustrated, I expressed my anger on Google+. A friend of mine, Joaquin, pointed out both the cause and a workaround of the new Lion's behaviour.

It turns out that Lion is performing periodic local backups that will be flushed upon your time machine disk when connected. Thinking about versions, aren't you? Anyway, that's also why the new /.MobileBackups folder into your OS X hard disk is eating up disk space. Never noticed purple and white snapshot lines in Lion's Time Machine user interface? White ones are local backups, purple ones are "regular"time machine backups on an external disk. Well, local backups are kept for 8 days and they'll be taken only if you've got enough space on your disk. However, if you, like me, manage huge quantities of big files (such as a camera RAW files), this feature can start eating up an enormous amount of space.

If you, like me, feel like turning off this amazing feature you can use the following command:

$ sudo tmutil disablelocal

Should you change your mind about it, you can always turn it on again using:

$ sudo tmutil enablelocal

These are just the kind of options that should be accessible in the user interface.

Hope this helps you.