Booting RHES4-U2 from mirrored disk - SOLVED

[Ramer Ortega]

Thanks Alfred.  Yeah, I realized, it was a chicken-and-egg situation.

As I was waiting for reply, I found this document:
Remote Conversion to Linux Software RAID 1 by Warren Togami
URL: http://togami.com/~warren/guides/remoteraidcrazies/

Step 25 of the document is about reinstalling GRUB on BOTH disks which 
is similar to what you suggested.  I followed the steps in Togami's 
document (which is an interactive session of grub) and my server can 
boot from the mirrored disk now.

Thanks once again.


Alfred Hovdestad wrote:

> The problem is that you are using software raid, so there is no raid 
> device /dev/md0 until the OS boots, but you can't boot because there 
> is no boot device (catch-22).
>
> We recently worked through a similar install on an HP xw9300.  We 
> submitted our findings to HP, they verified them, and the last I 
> hearde was that this was an "unofficial" document (I don't know if 
> they ever supported the procedure, but they did verify that it worked).
>
> It looks lke you have the raid system configured, and the OS 
> installed.  All that remains is to duplicate the boot partition.  Here 
> is the procedure for duplicating the boot partition:
>
>
>
> Duplicating the Boot Partition:
>
> 1. The first step you need to accomplish is to boot into “single user” 
> mode. The easiest way to accomplish this is to enter “init 1” at the 
> command prompt in a terminal window. NOTE: You will need to be logged 
> in as ROOT to perform these steps
>
> 2. At the prompt, type in "vi /etc/mtab". Locate the entry /dev/md0 
> and replace it with /dev/sda1. Exit vi, saving your changes. Make note 
> of the changes made in this and the following steps as they will need 
> to be restored to their original values in the final step.
>
> 3. Next, enter "/sbin/grub-install  /dev/sda" and press ENTER, this 
> will place the GRUB Boot Loader in the boot sector of  the first HDD. 
> When the operation is complete it will report back that the 
> installation has completed and report any errors if detected. Now, 
> restore /etc/mtab to it's original contents.
>
> 4. Next, type in "vi /etc/mtab" again. Locate the entry /dev/md0 and 
> replace it with /dev/sdb1. Exit vi, saving your changes.  Type in "vi 
> /boot/grub/device.map" and replace the entry “/dev/sda” with 
> “/dev/sdb”, exit vi, saving your changes.
>
> 5. Next, enter "/sbin/grub-install  /dev/sdb" and press ENTER, this 
> will place the GRUB Boot Loader in the boot sector of  the second HDD. 
> When the operation is complete it will report back that the 
> installation has completed and report any errors if detected. Now, 
> restore /etc/mtab to its original contents and then restore the 
> content of /boot/grub/device.map to its original contents.
>
> 6. Reboot the system, the RAID1 is now completed.
>
>
>      Alfred Hovdestad, RHCE
>      University of Saskatchewan
>
>
> Ramer Ortega wrote:
>
>> I'm trying to install RHES4-U2 in a mirrored SATA disks.  I have 2 
>> disks and during the installation, I defined all the partitions as 
>> Software RAID and eventually created RAID1 for each partition, 
>> including the /boot partition.
>>
>> Install went smoothly but after the completion and during reboot, the 
>> screen simply displays "GRUB".
>>
>> I booted from the install CD and entered the rescue mode to check the 
>> partitions and the grub.conf.  The contents of /etc/fstab rightfully 
>> shows that all my partitions are mapped to the corresponding /dev/md? 
>> devices.
>>
>> My question is, is there any limitation on grub to boot from a 
>> mirrored /boot partition?
>>
>> Is there any other area that I should be looking at?
>>
>> TIA
>>
>