[TriLUG] /boot Partition Sizes

[Jeremy Portzer]

On Wed, 2004-10-20 at 18:32, Tommy Williams wrote:
> Can anyone explain (or point me in the right direction) why Fedora
> Core requests a boot partition size of at least 75mb. It's been a long
> time since I played with a boot loader, and remember that boot loaders
> didnt take up much more than a few megs, (or I could just be
> remembering some things wrong).

The boot loader itself isn't very big, but the the /boot partition also
holds  kernel images and related files.  The boot loader must be able to
read this partition in order to read the 2nd stage of the boot loader
itself, and the kernel images.  Certain BIOSes have restrictions on
where they can read files from, and thus the /boot partition should be
placed wholly within the first 1024 cylinders of your  hard drive. 
Newer BIOSes usually do not have this restriction, so you often don't
need a /boot partition at all.  In the Fedora Core installer, if a /boot
partition is created, it will be sure to put it near the start of the
drive for this reason.

Once the Linux kernel begins loading, its device drivers take over from
the BIOS default drivers, so these restrictions are no longer an issue. 
That's why it doesn't matter where your / or other paritions are, even
if you do have a BIOS with this problem.

On a new system, I have generally been allocating 200 MB for my /boot
partition, just to allow room for various kernels.  If you are upgrading
your kernel frequently, or testing different kernels, you may need this
extra space.  If you are always going to use the default kernel (and
replace it with the kernels from the updates), then you probably don't
need even the 75 MB that's recommended; 30 or 40 MB may suffice.  But
with today's hard drive sizes, I don't see a big reason to skimp.

Try it without a /boot partition at all, maybe your BIOS will work
fine.  Then this whole question of /boot parition size will be moot. 
:-)

Hope this helps,
Jeremy

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| Jeremy Portzer        jeremyp at pobox.com      trilug.org/~jeremy     |
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