HFS+ is the files system used on many Apple Macintosh computers by Mac OS. You can mount this filesystem in Ubuntu with read only access by default. If you need read/write access then you have to disable journaling with OS X before you can continue.
In OS X, open a terminal and type:
You will obtain an output similar to the following:
/dev/disk0 #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *256.1 GB disk0 1: EFI 209.7 MB disk0s1 2: Apple_HFS Macintosh HD 230.0 GB disk0s2 3: Apple_Boot Recovery HD 650.0 MB disk0s3 4: Microsoft Basic Data 25.2 GB disk0s4
Note down the identifier of your OS X partition. It is of type "Apple_HFS" and usually named "Macintosh HD". In our example, it is disk0s2.
To disable journaling, type the following in the terminal:
sudo diskutil disableJournal volumeName
Where volumeName is the previously discovered identifier for OS X partition (disk0s2 in our example).
There was a bug in certain versions of OS X that would allow this command to complete successfully, but still not disable journaling. In order to fix this issue, you may need to enable journaling first with the command:
sudo diskutil enableJournal volumeName
Disabling journaling on your main OS X partition is not recommended however as journaling is an important feature of any filesystem that can prevent damage and data loss: http://en.wikipedia.org/wiki/Journaling_file_system
Other information which may be useful can be found here: http://en.gentoo-wiki.com/wiki/Hfsplus