I've got a late 2010 MacBook Air that came with OS X 10.6.6 installed; I have never upgraded it to 10.6.8 Snow Leopard or to 10.7 Lion.

I dual boot with Windows 7 installed using boot camp. I use rEFIt as my boot loader.

Disk Utility in OS X shows:

  • Macintosh HD is partition 2
  • partition 3 is an empty FAT partition
  • Windows HD is partition 4

I don't know why partition 1 doesn't show up there. In Windows under Disk Management it shows up as 200 MB (GPT Protective Partition)

When booting, rEFIt gives me these options:

  • Boot to Mac OS X
  • Boot to Windows on Partition 4

If I upgrade OS X to Lion, is there any risk of breaking my Windows install, messing up my Windows partition or the boot loader or anything like that?

2 Answers 2


You won't break Bootcamp by upgrading Mac OS X, but it may complain on attempting the upgrade that it cannot do it. Some configurations of Bootcamp from older macs put the partition for Bootcamp as the 3rd partition on a disk. In these cases, Lion is unable to create a recovery partition at the start of the disk, as the Bootcamp partition won't boot from position 4.

But you can check for this, look in Disk Utility, and if you only have 2 partitions, then you're likely looking peachy :)

  • I updated my question to show the partition information. I had to use rEFIt as my boot loader because I couldn't boot from USB without it. This is the process I used to install Windows which resulted in it being installed on partition 4: apple.stackexchange.com/a/8204/3551
    – wweicker
    Apr 3, 2012 at 23:24
  • I can't guarantee what will happen, but I think it will fail to install with a nice error, complaining about pre-reqs. Sorry to be non specific, but that boot config is a little custom shall we say
    – stuffe
    Apr 4, 2012 at 20:23

If you're doing just a straight upgrade and not a complete rebuild, then it should be absolutely fine. OS X upgrades are aware of other partitions so it shouldn't break anything.

By the way, I know this is not question, but I used to use Boot Camp, but find Parallels a much better experience overall. Disclaimer, I'm a .net developer.

  • With the SSD making booting so fast I've never felt the need to spend money on Parallels... I've been happy dual booting so far.
    – wweicker
    Apr 3, 2012 at 23:21
  • hey wweicker. Yeah for me it's not a performance issue. I just prefer being in OSX for everything, but having Visual Studio there for coding. That way I'm dealing with OSX as the OS and windows just as the apps, I don't have to deal with the os. So I can still have adium, sparrow, twitter, terminal, and have windows just for coding. Just much nicer for me. Only useful in coherence mode I find though.
    – andy
    Apr 4, 2012 at 4:17

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