Re: Help installing grub

[Jordan Uggla]

On Tue, May 29, 2012 at 7:30 PM, Yan Seiner <address@hidden> wrote:
> I need some help with a custom install.
>
> I have a client that I access via a remote connection.  Their server has two
> physical drives set up in a software RAID-1.  To make a long story short,
> through a "perfect storm" series of events, they lost both hard drives.  I
> shipped them a backup of their data and their local admin got the server
> running on a single drive.
>
> I figured I could set up the other drive as 1/2 of a RAID array, install the
> data, and then reboot the server with the RAID running and complete the
> mirroring operation.  I mostly followed this process:
>  https://wiki.archlinux.org/index.php/Convert_a_single_drive_system_to_RAID
>
> I am running into trouble getting a valid boot sector on the new raid drive.
>  This is the first time I've dealt with GRUB 2, and I am not sure how to set
> it up to boot off of /dev/md1 (the boot partition).
>
> Here's what I have:
>
> /dev/sdb - current boot drive with GRUB installed correctly.  This boots
> just fine.
> /dev/sda - new half-array drive without GRUB installed.
>
> Q:  How do I get GRUB installed so it boots off of /dev/md1 (/dev/sda2)?

To install grub you need to use grub-install. If you were already in
the booted system, with the array already setup normally, you would
simply run "grub-install /dev/sda && grub-install /dev/sdb". It
doesn't sound like that's the case for you, but it's hard to tell and
that information is critical. How / where is /dev/md1 going to be
mounted when you run grub-install?

>
> I am doing this all via ssh; I have no physical access to the server, so
> some way of checking that the system will actually boot correctly would be
> welcome.

This is possible via qemu (but you need to be *very* careful). I will
go into more detail on this after you've answered my above question.

-- 
Jordan Uggla (Jordan_U on irc.freenode.net)