Booting RHES4-U2 from mirrored disk - SOLVED
Ramer Ortega
ramer.ortega at hotpop.com
Fri Jan 27 17:08:39 UTC 2006
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
>>
>
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