On 01/24/2014 09:33 PM, Les Mikesell wrote:
> On Fri, Jan 24, 2014 at 1:30 PM, Ljubomir Ljubojevic <centos@xxxxxxxx> wrote:
>>>
>>> and, even if you have the boot loader on both drives, there's no
>>> guarantee your BIOS will boot from the 2nd one. Disks can partially
>>> fail in nasty ways that might allow the already-running system to stay
>>> up on the other half of the mirror, but when the drive is 'tested'
>>> during power up boot sequence, it could hang the system.
>>>
>>
>> True, but forwarding of root mail to admins e-mail address will warn
>> about crash of mirror, so physical intervention of choice can be made. I
>> think manual change in BIOS is of little consequence if system will boot
>> off of surviving disk(s).
>
> Doesn't grub need to know the bios disk id for subsequent stages of
> the boot and where to find the root filesystem? I think it matters
> whether or not bios remaps your 2nd drive to the first id.
GRUB boots first partition on a given disk, and then kernel boots file
systems from RAID's. Once /boot RAID is mounted, any changes are written
to all disks.
>
>> And if disks can be hot-swapped then only concern is that GRUB and /boot
>> survive the crash.
>
> And if you know how to do a rescue-mode boot and reinstall grub, you
> can fix that too.
>
--
Ljubomir Ljubojevic
(Love is in the Air)
PL Computers
Serbia, Europe
StarOS, Mikrotik and CentOS/RHEL/Linux consultant
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