Moving a server over to a RAID

[Mike A. Leonetti]

 (2010年08月19日 14:04), Tom H wrote:
> On Thu, Aug 19, 2010 at 11:27 AM, Mike A. Leonetti
> <mikealeonetti at gmail.com> 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.
> How many disks can your computer handle simultaneously?
>
> If three, then boot from your current install with all three, do a
> full backup, install mdam, create the raid array on the two new disks,
> boot from a Live CD, copy your data to the array (you will have to
> install mdadm in the Live CD environment and activate the arrray),
> modify the fstab, update the initrd, and install grub.
>
> If two. follow the same as above but create an array either with one
> disk or with two disks with one missing. Once you replace the old disk
> with the second new one, either grow the array or sync it.
>
It should be able to handle up to 4, which is fine. But according to
Rashkae this setup won't work because of the following (to quote him):
> 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.) 
He also responded to this thread. I thought the same way you did until I
read his comments.