From: Scott Silva Sent: October 10, 2007 15:15
on 10/10/2007 2:46 PM Hugh E Cruickshank spake the following:
From: Les Mikesell
Hugh E Cruickshank wrote:
From: Les Mikesell Sent: October 7, 2007 18:53
Then reinstall grub on the drive.
Now I have some questions:
Since the /boot partition was mirrored and will be restored on the new sda drive I do not really want to do a full grub install. From what I have read that will overwrite existing /boot/grub/grub.conf file. So I just want to write the MBR on the drive. How to I do that (the docs I have found were rather unclear on that aspect)?
Can a install grub on the replaced boot drive with the system still running?
Yes, after the /boot partition re-sync has completed, execute grub and:
root (hd0,0) setup (hd0) quit
If you aren't able to keep the system running while doing the swap, you can also do this from the rescue mode boot, but you should have the contents on the /boot partition first.
Sorry to be obtuse here but I just want to make very sure of what I am doing before I do it. Will the "setup" command only write the MBR?
From my reading the GNU GRUB manual I got the distinct impression that
the "setup" command will also write/rewrite the /boot partition (which I would like to avoid). The documentation for the setup command states:
Set up the installation of GRUB automatically. This command uses the more flexible command install (see Section 13.3.18 [install], page 44) in the backend and installs Chapter 13: The list of available commands 49 GRUB into the device install device. If image device is specified, then find the GRUB images (see Chapter 10 [Images], page 29) in the device image device, otherwise use the current root device, which can be set by the command root. If install device is a hard disk, then embed a Stage 1.5 in the disk if possible. The option �--prefix� specifies the directory under which GRUB images are put. If it is not specified, GRUB automatically searches them in �/boot/grub� and �/grub�. The options �--force-lba� and �--stage2� are just passed to install if specified. See Section 13.3.18 [install], page 44, for more information.The second paragraph tends to imply that /boot/grub will be written to by default and I do not think that this is what I want to happen.
Thanks again for everyone's input (especially Les). It is greatly appreciated.
What "setup" command?
That would be the grub setup command.
You boot from a rescue disk if your system isn't running already. If booting from rescue disk chroot to your installed files. execute grub at its prompt run the following; root (hd0,0) setup (hd0) quit That should let you boot into your stuff.
I know that will let me boot but that was not what I was asking about. As per the documentation I quoted it appears that the grub setup command will overwrite the /boot partition that has been restored from the mirror drive. As far as I can see that is not desirable. All I want to do is install the GRUB MBR and leave the contents of the /boot partition intact.
My question is basically will the grub setup command only install the MBR or will it also overwrite the /boot partition as well?
Regards, Hugh