software raid

[Jonathan Hudson]

On Thu, 25 Oct 2007 18:03:22 -0300
Marcelo Magno <mmagno at blumar.com.br> wrote:

> Hi folks.
> 
> I Have an ubuntu server installed with one sata disk.
> 
> Is there a way to add another disk and arrange it in a software raid
> mirror with the first disk, without having to reinstall all the system? 
> 
> What needs to be done, to have the other disk booting in case the first
> one fails?
> 
> Is there any howto that teaches how to have this done?
> 
> Thanks in advance,
> 
> 
> Best Regards,
> Marcelo Magno
> 

It's quite easy. 

* Setup the second disk as a member(s) of a 2 disk raid,
with one disk missing. 

* Copy the complete contents of the first disk to the second

* Boot off the second disk

* Repartition the old disk, e.g.

  # sfdisk -d /dev/sdb | sfdisk /dev/sda

* Add the old disk into the raid array

* Have a beer while linux sysnc the arry.

* Reboot (if you wish).

There's a certain amount of detail in ensuring grub is set up correctly
and all the device nodes exist, but google can help here.

I've done this on several machines, without any problem.

-jh