Moving a server over to a RAID

[Rashkae]

Mike A. Leonetti wrote:
>  I have a server now that has one drive and is not set up on a RAID
> using Ubuntu 8.04.
> 
> What I was going to do was boot with a Linux recovery disc, create a
> RAID1 manually with mdadm on two new drives, and then copy all of the
> data onto that then redo the boot partition.
> 
> My question is, when I reboot, will Ubuntu automatically detect the RAID
> for me or are there modules I have to install ahead of time to make sure
> the RAID gets detected? Also, would anybody else handle the situation
> differently :D.
> 

There is going to be one hurdle you'll need to get over.. I forget the 
exact command I used to recover, but I'll give you the overview.

When raid array's are created, they are given a "hostname", which, by 
default, will by the system hostname.  By default, mdadm will not 
auto-assemble raid arrays from a different hostname (to prevent 
misunderstandings when hard drives are moved between different systems.) 
  Unfortunately, Ubuntu must assemble the raid arrays from the Initrd 
system, which will probably not contain your hostname unless you have 
customized it.  I encountered this problem when I created the new array 
from the existing system, I do not know if you will have this issue when 
creating the array from the rescue cd.

When I tried to reboot the system, it was unable to mount the root 
filesystem.  However, initrd dropped me to a busybox shell, from which I 
was able to run mdadm with options that would assemble the correct array 
*and* update the hostname of the array, (which I think is simply "", ie. 
empty, in initrd.)