[CentOS] Re: Stuck at GRUB

[Ugo Bellavance]

Christopher Chan wrote:
> Ugo Bellavance wrote:
>> jancio_wodnik at wp.pl wrote:
>>> Christopher Chan pisze:
>>>>
>>>>>>>> grub cannot find its second stage. Are you booting from a 
>>>>>>>> mirrored partition?
>>>>>>>
>>>>>>> Yes
>>>>>>
>>>>>> What could be a solution?  And what could have happen upon the 
>>>>>> reboot?
>>>>>
>>>>> That is weird.  I just re-installed centos5 and it is now booting 
>>>>> properly.  What could I do to avoid this situation in the future?
>>>>>
>>>>
>>>> IIRC, RHEL4 does not properly handle installation of grub on 
>>>> mirrored partitions and therefore Centos4 suffers from the same 
>>>> problem.
>>>>
>>>> RHEL5 does it properly now as you can see. This has been a long 
>>>> outstanding problem of anaconda.
>>> Yeap, this is true. After installing centos4 on RAID1 disk (software 
>>> raid) i always do:
>>>
>>> grub
>>> grub>device (hd0) /dev/hdc
>>> grub>root (hd0,0)       grub>setup (hd0)
>>>
>>> where /dev/hdc is second RAID DISK (it could be whatever: /dev/sdb1 etc)
>>>
>>> So system is booting form first or second riad1 disk
>>
>> Ok, so to sum up from what I understand of my problem:
>>
>> Installation of CentOS4 -> Installs grub only on one HDD partition out 
>> of 2, in the mirror.
> 
> Well, I believe you chose md0 or something to install grub on right?
> 
>>
>> One disk fails, the one that has grub
> 
> Not necessarily. All it takes is a change in the sequence of disk 
> assignment.
> 
>>
>> System won't boot because it can't find grub on the other drive.
> 
> Correct. It needs to be instructed to look on its own drive.
> 
>>
>> If I had centos5 there in the first place, the setup would have taken 
>> care of installing grub on the 2 mirrored raid partitions.
>>
>> Am I right?
> 
> Yes.
> 
>>
>> Is there a way to know where grub is installed?  I have a few servers 
>> running in RAID 1 software for /boot, I gotta fix this.  If I can't 
>> tell whether it is installed or not, is it dangerous to re-install it 
>> using the command above?
>>
> 
> So long as you have all the necessary grub files, there is not much 
> danger. Even if you are missing a config file on this side of the mirror 
> (impossible...) so long as you load grub stage 2, you will have the 
> power you need to continue if you have access (eg: via serial)

I was talking about all my others centos4 machines..