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I have on my computer an existing primary partition with Windows 7 on it. There are also two OEM factory partitions which I do not want to mess with. I would like to use the remaining space for an extended partition with several logical drives. Will there be any issues WRT booting from any or all of these partitions?


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How many partitions show in disk management? – Moab Jun 1 '11 at 1:18
up vote 1 down vote accepted

As mentioned, if your machine has PC/AT or PC98 firmware, then you won't be able to bootstrap such secondary volumes directly from the firmware. You'll need a boot manager program as an intermediary. Boot managers fix up the BIOS Parameter Block fields of such volumes on the fly, so that the boot loaders in the operating systems' volume boot records work. The PC/AT and PC98 firmwares' boot record loaders do not do this; nor does the loader code in any common MBR bootstrap loader.

You'll also have installation difficulties. Some operating systems are designed on the basis that people don't use such boot managers, and therefore go to some effort to ensure that their boot loaders are installed in a primary partition. To varying degrees, you'll have to fight the operating system install utility on such operating systems.

And then, of course, there's the 2TiB limit. With the MBR partitioning scheme you won't be able to even have partitions above the 2TiB boundary. But a lesser known facet of the 2TiB problem is that even if you switch to the EFI partitioning scheme you still won't be able to bootstrap an operating system via the volume boot record of any FAT, HPFS, NTFS, or other partition with a BIOS Parameter Block that crosses over or resides above the 2TiB limit. Bootstrapping boot volumes above the 2TiB line requires switching from the VBR boot mechanism to machine firmware that supports EFI boot loaders and the like (and of course to operating systems that have such EFI boot loaders).

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OK, so it's more trouble than it's worth. Thanks! – posfan12 Jun 10 '11 at 23:14

The "legacy" bootloader cannot boot from logical partitions; you will need to find an alternate bootloader if you want to boot off one.

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