Trying to understand the boot process

[eggrolls]

So right now I have two hard drives and they're set up like this:
http://img10.imageshack.us/img10/1364/partitions.jpg

F = Windows XP
D = storage
C = Windows 7
E = Windows Vista

I installed the OS'es in this order: XP, Vista, Win7. The installers automatically set up everything so that each OS is bootable from the OS selection screen. Since I never had to mess with the bootloaders, I don't really understand how they work.

So I have a few questions:

How many bootloaders can each physical drive have? (I'm guessing one)

The Windows Vista/7 bootloader can't boot XP directly, but merely points to the XP bootloader. Is that right or not?

If the above is correct, which bootloader is on which drive? (Or, how would I find out?)

If I install Linux (GRUB) or OS X onto either drive, will that cause one or more of my Windows partitions to become unbootable?

Any help is greatly appreciated.

 

[Billb2]

There is only one boot loader, though it can call another boot loader.
The boot loader can be on any drive/partition. The code loaded from the first sector of the boot drive (the boot sector) just has to point to it. And that boot loader has to point to subsequent boot loaders wherever they are.

Linux installs it's own boot loader. You can either modify it to also point to the Windows boot loader or modify the Windows boot loader to point at it.

Windows XP boot loader is Boot.ini. Vista/Windows 7 is BCD.exe. Though they aren't the actual boot loaders, just the things that identify where the boot loader is installed.

 

[degibson]

If I install Linux (GRUB) or OS X onto either drive, will that cause one or more of my Windows partitions to become unbootable?

I know that GRUB can boot XP. I haven't tried with Vista or 7.

 

[Nothinman]

How many bootloaders can each physical drive have? (I'm guessing one)

Well each physical drive as one MBR but there is a boot record on each partition as well. That's how boot loaders like GRUB boot Windows, they just load up the boot record from the designated partition and pass control to it.

If I install Linux (GRUB) or OS X onto either drive, will that cause one or more of my Windows partitions to become unbootable?

Possibly until you fix up the GRUB configuration, it might not guess properly for all of them.

 

[Rifter]

GRUB picked up my Vista fine, long story but i installed vista first then Mint 6 and GRUB correctly picked up Vista and they are both on the boot menu i did not need to edit anything.

 

[postmortemIA]

Originally posted by: Rifterut
GRUB picked up my Vista fine, long story but i installed vista first then Mint 6 and GRUB correctly picked up Vista and they are both on the boot menu i did not need to edit anything.

like Nothinman said,

GRUB will not remove windows boot loaders since they lie on windows partition. It is almost trivial to set up GRUB to load these entries for booting the windows spartitions.
GRUB will however take over the master boot record (as a default option for most distros)
it is a general rule in windows world: anytime you install new windows, it will rewrite master boot record with entry that works with its boot loader. It will also put new boot leader on whatever it decides is first partition.