I'm curious about whether possible to install OS X on multiple partitions. I am already using several user accounts in one installation, putting different accounts into different installations of OS X.

  • It might behoove you to work on your accept rate. If it's true that none of your questions have acceptable answers, post a bounty on them or edit the question to elicit better answers.
    – Cajunluke
    Commented May 3, 2012 at 17:34

3 Answers 3


This has nothing to do with Bootcamp. Simply split your hard drive into several partitions with Disk Utility, and run the OS X installer. You will be able to choose whichever partition you want to install onto, and switch between each by pressing on startup.

However, please note that this is not compatible with Bootcamp. I.e. you won't be able to have a Windows partition, at least not with Bootcamp (you'd need a solution like rEFIt).

Regarding whether you'd need to buy OS X again or not: as per the OS X EULA:

This License does not allow the Apple Software to exist on more than one computer at a time

…which I'd take for “it may exist several times on the same computer at a time”.

I know that's not what you asked for, so I'll keep it as an aside, but I can't resist saying it: this “partitioning” habit really is a switcher thing. There's no need for that under OS X, especially if you fully encrypt each partition (which I'm curious about, by the way).

The only reason I personally have two partitions is because I am totally dependent on my machine for my daily work, and I keep another OS in case of system corruption. But I aliased my user folder on the emergency partition to the one on the main drive, as an OS without my data is as useless as no computer. This fear of “a trojan” that would kill your system is irrational, and this setup will cost you much more in terms of maintenance (rebooting, keeping two systems updated in parallel…) than the advantages it will bring.

  • The concern about malware is not irrational at all. The goal of any malware programmer is to get root access, and when achieved this lets them infect or replace core OS files.
    – Mithras
    Commented Jan 19, 2012 at 15:42
  • @Mithras Malware under OS X does not have any sufficient proven cases to be anywhere close to justifying duplicating the OS. Well, that could be subjective… But what is not, is the idea that malware has any interest in making your system unusable. Adware might have that side-effect (too many pop-ups, whatever, once again utmost uncommon under OS X). Anyway, under OS X, there is no other infection vector than one's own stupidity (seeing all reviewed malware asked for admin password), which having two systems won't save you from.
    – MattiSG
    Commented Jan 19, 2012 at 18:29

You can run multiple versions of OS X on one drive. I have done it so I could have several versions of OS X available.

However, if the only reason is that you are worried about a trojan etc., then it's not worth it. If a trojan is installed, it will see and it can affect all partitions.

  • The idea was that I was going to encrypt each partition separately.
    – Mithras
    Commented Jan 18, 2012 at 20:15

As an alternative, you could just have multiple users on the same partition. The "play" account (and thus the applications that it runs, including any trojans) may be configured not to have the right to write into the system folders, nor the folders of the "work" account.

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