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Is my PC able to boot from my external USB formatted to Mac OS X Extended Journaled?

It works fine on my Mac, but I want to boot from it on my Windows (PC).

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Do you mean you want your PC to run Windows from the external drive, or you want your PC to run Mac OS X from the external drive? – Paul D. Waite Apr 4 '10 at 20:31

Windows can't read or write HFS+J (Mac OS Extended, Journaled) natively. Neither can the Windows installer. So you won't even be able to install Windows onto an HFS+J partition.

Even if you manage to use some other tool to clone/copy a Windows installation onto an HFS+J partition without mangling it, the Windows booting code wouldn't know how to read HFS+J, so it wouldn't be able to boot from it.

There are third-party products like MacDrive that allow Windows to read and write HFS+J partitions, but products like that don't load until later in the boot process, so they don't enable booting from HFS+J.

The best you could do is take that external drive, make sure its low-level partition map format is GPT (GUID Partition Table) as opposed to MBR (Master Boot Record) or Apple Partition Map, and add a FAT or NTFS partition to it (possibly by first making room by shrinking the HFS+J partition using Mac OS X Disk Utility). Then you could install Windows on the FAT or NTFS partition so you can boot Windows from there.

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He did not mention, that he wants to boot windows. I think he wants to boot OS X. – lajuette Apr 5 '10 at 15:42
He said he wants to "boot from it on his Windows". That's a bit ambiguous and poor English, but I think it's reasonable to think he wants to boot Windows. @lajuette – Spiff Apr 5 '10 at 16:51

If you are talking about booting OS X (without illegal mods):

NO WAY (sorry).

If you want to boot another OS: You need a boot manager that understands hfs+. And an operating system on that partition that is compatible with your hardware and understands hfs+. That means no Windows for you. And if you want to boot Linux you're probably better off using ext3,4 or something like that.

Not a good idea.

Why do you want to boot from that partition? Do you just need access to the data?

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Why? What problems will he encounter? – Kevin M Apr 4 '10 at 19:59
What problems will he encounter trying to boot from a filesystem the operating system has zero support for? Are you kidding? – Hasaan Chop Apr 5 '10 at 2:35
@NSD: when I added my comment, the answer was only 4 words long: "This is not possible". I was asking those questions to make a more helpful answer. – Kevin M Apr 5 '10 at 17:21

Apple's bootloader will allow it. Other than that, for a PC, it requires a custom kernel for Mac OS and possibly an alternate bootloader for your PC, and running Mac OS X on a non-Apple machine is illegal.

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Do you mean ...will **not** allow it...? – Moshe Apr 4 '10 at 19:43

You cannot boot to Mac OS X from a non-Mac, regardless of what the underlying filesystem is. Or, if you're looking to go that way, why do you want to put Windows on a Mac OS X Extended Journaled filesystem?

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Putting Windows on a HFS+ filesystem won't work that easy. There's no native support for it in Windows and only a driver from Apple, that hasn't been released as standalone driver. – lajuette Apr 5 '10 at 15:53
@lajuette: which is precisely why I asked my question. The asker is in for a world of pain if he tries to do so. – Kevin M Apr 5 '10 at 17:25

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