While installing grub using grub-install command, do we specify root partition or boot partition?

Thanks

If a separate boot partition then that is the choice unless you want it to install to the MBR.

Excuse me, would you please be more specific/expand that answer? I'm currently wondering about installing grub myself, and I'm a little slower than the rest. :-P

Thanks!

This is answering a different question than OP is asking.
Something needs to be in the mbr--if you put GRUB in a partition boot sector, you still need to point to it somehow.

To the original question: You have to tell the GRUB installer where /boot is---ie where it will find it's config files, kernel, etc.

My site (link below) has an article on booting which may be useful...

I enjoyed your article and gave a lot of insight. Thanks!

But my question is still there. where to install grub-install?

root partotion or boot partition?

OK--so you mean "where do we install GRUB"??
It is neither of the above...

Normally, GRUB gets installed in the MBR. The other typical option is to put it in the boot sector of a partition. If you do it this way, you then have to have SOMETHING in the mbr that points to that partition--eg using the "chainload" command.

If you have a Linux install with separate partitions for /boot and /, then I guess GRUB would go in the boot sector of the partition which contains /boot.

let me repharse it again.

To install 1st stage grub we use grub-install /dev/hda

in /dev/hda part should we specify the location of our boot filesystem or root file system? or even if they are on the different partition we still use only grub-install /dev/hda command.

thanxx......

grub-install /dev/hda puts stage1 on the MBR of hda---it has nothing to do with where /boot or / are.

To install GRUB (by any method), you have to specify 2 things:
Where the /boot directory is
Where to install GRUB

grub-install apparently defaults to assuming that /boot is in /, and is all in the current Linux partition.
Note from the GRUB manual that the "native" method--using the GRUB shell--is preferred. In this latter method, the "root" command is required:
grub
root (hdX,Y) tells grub where /boot is
setup (hdX) installs grub in the MBR

Look at the booting article at my site--link to the GRUB manual is there.