Re: Partition logic?


"Ron Hardin" <rhhardin@xxxxxxxxxxxxxx> wrote in message
news:438D4648.17E9@xxxxxxxxxxxxxxxxx
> Jim wrote:
> > The MBR can hold up to FOUR partition addresses. Besides the "type"
> > indicator, there's an active/inactive field as well for each partition.
> > When that's set to ON, that partition is recognized as the bootable
> > partition. When the BIOS loads the first sector from the HD (which is
the
> > MBR), the MBR boot code looks for the first partition marked active and
> > boots that partition based on the address stored there.
>
> Can I have only 4 partitions then? or is there some indirect addressing
> to get at others.
>

Well, to be precise, you can have either 4 primaries, OR, 3 primaries and 1
extended. The extended partition can have one or more (essentially
unlimited) logical partitions. Usually logical partitions are used
exclusively as DATA partitions since they can not be *officially* booted due
to their indirect addressing (but like anything else, there's always an
exception, ppl have found ways to make the OS boot from the extended
partition, including me, but MS doesn't officially support it, so for this
discussion, let's assume it doesn't).

I almost hesitate to mention it, since it tends to open a can of words, but
just for informational purposes, I use BootIt NG, which does allow me to
have MORE than 4 primaries, indeed, as many primaries as I want. It's made
possible by the way the BootIt NG boot manager manages the MBR. It
dynamically builds the MBR before turning it over to the boot loader! So
you can define many, many partitions using BootIt NG, then define bootable
configurations that define which partitions you want to be loaded in the
MBR. When you select that configuration for booting, the BootIt NG boot
manager updates the MBR to reflect those configuration options, then passes
control to the boot loader. Unbelievably powerful and useful. But being
non-standard, you can't use other partitioning software to manage those
partitions (not that I need to, BootIt NG has its own partition manager and
imaging solution anyway, so the restriction isn't very important to me).

Anyway, just thought I'd throw that out there to make the issue even a
little more confusing, complicated :) As I said, when it comes to
computers, there always seems to be an exception to EVERY rule.

Jim




> --
> Ron Hardin
> rhhardin@xxxxxxxxxxxxxx
>
> On the internet, nobody knows you're a jerk.


.

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