[NTLUG:Discuss] cfdisk and bootable partition flag

[Terry]

On 1/11/06, ntlug at levelofdetail.com <ntlug at levelofdetail.com> wrote:

> I'm not currently having a problem, but am trying to understand the boot
> process better.
>
> Would there ever be a reason to toggle between two partitions as the
> boot partition?
>

Only if  you set up a dual [or multiple] boot system would you "toggle
between [two] partitions as the boot partition", ... and I don't know
if we'd necessarily call them "boot partitions", that's probably not
an accurate description, it'd probably be stated more accurately as
"boot targets", (even that doesn't sound exactly right, but close
enough I guess).

The modern computers we have today have the ability to toggle between
bootable drives, which is to say that you can simply change a bios
setting and boot from a different drive, but in each case, the bios is
looking for the boot information in the Master Boot Record of that
"bootable drive" for boot information that will hopefully point it in
the right direction to find a bootable kernel to load into resident
memory.

What grub or lilo does is depict a bootable kernel for your computer
to run on, which can be kept anywhere, and booted from anywhere, (at
least as far as Linux is concerned).

The MS Windows kernel can only be booted from the first partition of
the hard drive that is designated as the bootable drive.  Whereas, the
Linux kernel can be booted from any partition on any hard drive.  We
use lilo or grub as a boot loader that will point to the bootable
kernel at boot time and away you go.  BUT, lilo or grub must be
written to the Master Boot Record of the bootable drive, or the first
drive in your computer.

Lilo or grub can be configured to give you any number of boot options.
 Because of that, you can install as many operating systems or kernels
on your computer as you want, and, at boot time,  you may choose to
boot from any of those kernels or operating systems you want.

We can install as many Linux kernels as we want and configure them to
do all sorts of different tasks for us, they can all be placed in the
same partition, even the same directory, [/boot]  and grub or lilo can
be configured to allow you to pick and choose which Linux kernel you
want to boot.

You can have multiple hard drives, or big hard drives with multiple
partitions, and as many other operating systems as you want on these
additional hard drives and / or partitions.  Lilo or grub can be
configured to boot all of these different operating systems, any time
you want to use them, all set up and ready to boot - you can have
multiple operating systems on the same computer - you can have MS
Windows, BSD, Linux, OS2, ... you could have several versions of each,
just waiting and ready to boot any time you want or need them.
And that is why you'd want or need to toggle between [multiple] boot
targets. Not everyone would want or need to do something like that,
only experimenters or some of the more adventurous ones would.

Some of us  may actually _need_ to have different operating systems or
different kernels and we may be too cheap or lazy to build a different
computer for each one, so we just do it the easy way, and keep adding
more operating systems to the same computer.  It's really a pretty
efficient method if you think about it - it's like having several
different computers in the same box.