Removing one drive from a RAID 1 setup?

[Gabriel Ramirez]

On 08/26/2009 06:08 AM, Law Barstow wrote:
> On Wed, 2009-08-26 at 03:12 -0500, Bruno Wolff III wrote:
> 
>>>
>>> Why would it mess up grub? - I thought I would just need to edit  
>>> /etc/fstab . .
>>
>> Because grub might not be saved on both MBRs. Because removing one disk
>> might rename the other and depending on how you have grub pointing to
>> the conf file this could break as well (though is less likely).
>> Grub doesn't actually see the raid array, it uses the filesystem in
>> read only mode (which works because the raid info is at the end of the
>> partition). So there can be issues with pulling drives out of the array.
>>
> 
> I ran into this issue when one of my disks in a RAID 1 mirror died
> unexpectedly.  GRUB wasn't installed on the MBR of both drives so the PC
> wouldn't boot.  I also had the issue where the drives were renamed
> (/dev/sda died)

I saw something similar, in my case (raid level 1 mirror two SATA drives)

sdb died and the machine don't boot from sda alone,

well the boot process halt at the grub prompt instead of the boot menu
issuing a "configfile /grub/grub.conf" shows the boot menu and the boot
process continues normally

adding back the sdb restore the boot menu, without it sda boot
terminates in the grub prompt

Gabriel