[CentOS] Re: Please help! boot problem

[Scott Silva]

Mace Eliason spake the following on 5/1/2006 12:55 PM:
> 
> 
> Scott Silva wrote:
>> Mace Eliason spake the following on 5/1/2006 12:29 PM:
>>  
>>> Scott Silva wrote:
>>>    
>>>> Mace Eliason spake the following on 5/1/2006 12:13 PM:
>>>>  
>>>>      
>>>>> So from what I have read I would run grub-install /dev/sda ?
>>>>>
>>>>> I have setup the raid with
>>>>> /boot (100Meg)
>>>>> /swap (2gig)
>>>>> / (the rest)
>>>>>
>>>>> All 3 are mirrored.
>>>>>
>>>>> I don't want to mess this up sorry I am new to this.
>>>>>
>>>>> Mace
>>>>>
>>>>> Scott Silva wrote:
>>>>>           
>>>>>> Mace Eliason spake the following on 5/1/2006 10:58 AM:
>>>>>>  
>>>>>>               
>>>>>>> Hi,
>>>>>>>
>>>>>>> I have a setup with raid 1 and one drive has failed, and the other
>>>>>>> drive
>>>>>>> won't boot says missing os.
>>>>>>>
>>>>>>> I thought I had it setup and tested but it would appear that it
>>>>>>> wasn't
>>>>>>> setup to boot form either drive.
>>>>>>>
>>>>>>> How can I boot from the good drive that is missing the grub.
>>>>>>>
>>>>>>> I am thinking of using linux rescue when booting from the centos 4.2
>>>>>>> disc
>>>>>>>
>>>>>>> This is a production machine and I don't want to mess it up.
>>>>>>>
>>>>>>> Please help
>>>>>>>                         
>>>>>> Use linux rescue and you can fix grub.
>>>>>> http://www.gnu.org/software/grub/manual/html_node/Invoking-grub-install.html
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>  
>>>>>>                 
>>>> less /boot/grub/grub.conf and post please-- just to be careful.
>>>>
>>>> Okay I have booted with linux rescue and skiped the network setup, and
>>>> skiped the next part and gone right to the shell.
>>>>         
>>> If I type grub-install it says no such file or directory.
>>>
>>> I tried less /boot/grub/grub.conf same thing.
>>>
>>> I did boot with the centos cd as if I was installing and used manual
>>> partion to see if the partions where still there and they are.
>>>
>>> No sure what to do now.  I will try and search for  grub-install.  I am
>>> assuming that I am searching the cd?
>>>
>>> Mace
>>>     
>> You can't skip the part about mounting your existing system. You will
>> need to
>> do that, and after it mounts, run chroot /mnt/sysconfig.
>> That should make all the commands run on YOUR files instead of the
>> bootdisks
>> running system.
>>
>>   
> Okay I didn't skip this time and it did a search and says "You don't
> have any Linux partitions. Press return to get a shell. The system will
> reboot automatically when you exit from the shell."
> 
> What the?
> 
> If I goto the shell and run fsdisk /dev/sda it shows I have 3 partitions
> with /boot set for booting.
> 
> I do get that?
If you show a /boot partition you don't have software raid.
The partitions in software raid are type fd (linux raid).
Does the replaced drive show up?

With a scsi drive, the lowest number addressed drive in the chain will be sda.
So if you had an sda set as device id 0, and an sdb set as device id 1, and
removed the sda drive, what was sdb would now show up as sda. Scsi doesn't
have fixed addresses like ide.
If you had proper software raid, your partitons would be all of typd fd, and
you should have a matching set on each drive ( sda1 and sdb1 would both be
type fd and the same size ,etc...).


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