Moving a server over to a RAID

Mike A. Leonetti mikealeonetti at
Thu Aug 19 18:13:22 UTC 2010

 (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> 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.

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