Ask Different is a question and answer site for power users of Apple hardware and software. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have reviewed what has been written here regarding the Mac OS X Base System and I am still scratching my head.

The impetus for this inquiry is how these partitions interfere with booting problem resolutions. I have a 2008 Mac Pro running ML 10.8.1. These Base partitions ate not as "invisible" as one is led to believe. If I boot with the Option key to choose a boot volume, two Base partitions appear along with my primary boot partition and the Recovery partition. One problem is, when the boot drive selected in System Prefs is not "defined" in pram, the system attempts to boot from the first Base system (alphabetical?). The boot looks like booting in Verbose mode then followed by a restart only seconds after. Logs seem to indicate a Kernel Panic. Recently, due to boot difficulties, I attempted to use repair methods posted on These methods are problematic in themselves when my system "sees" bootable volumes that aren't actually bootable!

share|improve this question
So… What is the question? – duci9y Aug 25 '12 at 7:24
I want either get rid of them if they are not neccessay, or understand this better. Even Apple Geniuses do not know about this. No one seems to be seeing these volumes with an option-boot. – Franics Alexander Aug 25 '12 at 11:28
There are some problems with your questions. Fix your question and maybe I will understand it better. 1. define “Mac OS X Base System” 2. “these partitions” which partitions? 3. define “base partitions” – duci9y Aug 25 '12 at 11:35
I guess the point is, I cannot fully define what the are. That is the point. I am not the only one discussing this in these forums and elsewhere on the web. A lot of people are confused and want to know. These partitions are a construct of Apple. – Franics Alexander Aug 26 '12 at 2:48

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.