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I’m a fan of Time Machine. Actually I’m a fan of backing up data in general. Some might even say that I’m paranoid because of the number of different backup methods that I employ. Not only do I use Time Machine but I also do clone backups using SuperDuper! and backups to the cloud (offsite) using CrashPlan. Recently I realized that I hadn’t updated my clone backup that I carry with me as a safety precaution in case I have a hard drive failure while on the road, in a while. I plugged in my portable drive and began the SuperDuper! clone. However, SuperDuper! error’d out and when I checked the log it seemed that it was having an issue backing up something called “.Mobile Backup”. It was actually reporting that there wasn’t enough room to back this folder up, which I knew wasn’t right because the backup drive and the internal volume were the same size and therefore everything should fit. I began to wonder what this hidden folder was and after doing a little research I discovered that Mac OS X 10.7 Lion has implemented a local Time Machine snapshot! The purpose of this is for MacBook/MacBook Pro users who may be away from their regular backups for a while (traveling) to have a safety net for accidentally deleted files (not drive failures). It makes sense and it’s a nice thing that Apple is doing for us. However, not only was this folder screwing with SuperDuper!, it was also chewing up about 20GB’s of space. Now in fairness, Time Machine will not let it eat up all your internal hard drive space (as it does with an external drive)  and will automatically shave off backups if you get low on space and even stop doing local backups if necessary. However, I’d rather have my 20GBs instead of the safety net.


Luckily there’s a Terminal Command to Disable it:

Just launch the Terminal App and enter sudo tmutil disablelocal (if you ever want to enable it again just do: sudo tmutil enablelocal) After I disabled it I immediately gained 20+GBs of space back and my SuperDuper! clone worked as usual. Hopefully the guys at Shirt-Pocket software will fix SuperDuper! to work with this folder, but in the meantime I’m going to leave this feature off.


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4 Responses to Time Machine’s Hidden Local Backup!

  1. Bradley Dichter says:

    local snapshots only happens on laptops, not desktops where your TIme Machine target volume is likely always available. Shirt Pocket says their latest version is compatible with Lion. What version are you running?

    • Terry White says:

      Latest version 2.6.4.

      • Bradley Dichter says:

        Got this from Shirt Pocket on the subject:
        Sometimes, the .MobileBackups folder is in an uncopyable state. There are many solutions to deal with this:
        Repair the source volume (which will often fix the snapshot problem)
        Temporarily turn Time Machine off using its preference pane (which will clear the .MobileBackups folder)
        Force a Time Machine backup to occur (which should clear the snapshot as well by moving it to the ‘real’ backup)
        Disable local backups (if you don’t want them)
        Ignore the .MobileBackups folder entirely with a copy script
        We’d hoped that .MobileBackups would be copyable in most cases based on our testing, but unfortunately in the broader community (beyond our test group) problems occurred more often than we’d hoped due to the way Apple manages this pseudo-drive (it’s really quite weird internally). Given that, we’re not going to copy the local snapshot folder in the next update.
        –Dave Nanian

  2. Bradley Dichter says:

    If you use TimeMachineEditor, it turns Time Machine on and off as desired. When it is off, the local snapshots are cleared and then would be a good time for the scheduled SuperDuper! 2.6.4 clone process.