How to boot from one duplicated boot partition
 

I'm new for Fedora, I have the following quesion:

How to make a backup boot partition and how to use the duplicated boot partition to boot into your system?

what should be in the /boot/grub/grub.conf ? thanks

backup the boot partition smiply by copying it to another location.

restore a boot partition by copying it back
presumably this even means you have an unbootable system - so you would boot from the install CD with the "linux rescue" option. Mount the filesystem and cp the backup over.

You can run grub with
grub --config-file <file>

You can use a preset menue with GRUB, which defines /boot to be someplace else. The preset menue is only used if the normal grub.conf fails to load.

Didn't find any kernel options which would change where grub looks for grub.conf ...

Basically, most folks would recover a broken /boot partition by copying over.

A cute method - if your BIOS will boot from usb drive - is to install a small distro to an old HDD in a IDE-usb converter. Use this as an emergency rescue system.

I'm not sure everyone is talking about the same thing. To have a backup method of booting, you need a duplicate of the mbr--not the "boot partition" or /boot.

For example, if you have GRUB in the mbr on drive 1, and somehow it gets zapped--eg by installing Windows--you can always boot from a floppy that also has grub on it. No need to change grub.conf

first, I use the following command to duplicate the boot partition:

dd if=/dev/sda1 of=/dev/sdb1

then I change the grub.conf file as follows

title Fedro (Original Boot)
root (hd0,0)
kernel XXXXXXXXXXXX ro root=/dev/sda1 xxxxxx
tile Fedro (Backup)
root (hd0,0)
kernel xxxxxxxxxxxx ro root=/dev/sdb1 xxxxxx
after that, when the GRUB meau show up, I choose the second one. it is fail !
so, what is problem? thanks

How are you defining the "boot partition"? Do you mean the partition mounted at /boot?

Where is GRUB on this machine? eg in the first harddrive? floppy?

Referring to your initial post, you don't use the /boot partition to boot into your system--there is stuff that has to happen first.

please post the output of fdisk -l (ell, not one) (run this as root)