On OSX yosemite, a machine with limited disk space free.

In order to backup my iphone, I've linked the ~/Library/Application Support/MobileSync/Backup dir to an external drive.

iTunes, correctly displays the existing backups in that dir.

But iTunes backup, fails with an insufficient disk space free.

Is it failing to check the free space on the volume that the Backup folder is on?

The boot volume certainly does not have enough free space.

How can I work around this, without deleting data?

  • osx: 10.10.3 (14D136)
  • iTunes:

update: have tried on another machine (with sufficient space) still received the same error.

Suspecting bugs, or permissions issues.

  • I'm guessing it's looking at the free space of the container (hard drive) of the soft link - since there is no such thing as free space inside a folder (only the partition/drive containing a folder) and it thinks the folder is actually on the small drive, since that's where the link is.
    – tubedogg
    Commented Jun 19, 2015 at 5:19
  • I'm sure I've done this before successfully
    – bdargan
    Commented Jun 19, 2015 at 8:42

1 Answer 1


Perhaps it is better to move something else to the external disk, like the music or movies library. These are normally very large and thus this gives you ample space on the startup disk.

  • To make more space available is inconvenient. It requires more time and effort just to get the backup going and then it is inconvenient to use, as I need to lug an external drive around me when I want to access those files. I've also found iTunes defaults the preferences back to the default location if you forget to plugin the drive. Which other users in my household tend to do often. It's a great strategy to get Apple customers to buy bigger spec'd machines.
    – bdargan
    Commented Jun 20, 2015 at 22:50

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