[CentOS] CentOS 6.2 software raid 10 with LVM - Need help with degraded drive and only one MBR

Bowie Bailey Bowie_Bailey at BUC.com
Fri Mar 2 14:46:11 EST 2012


On 3/2/2012 1:01 PM, m.roth at 5-cent.us wrote:
> Digimer wrote:
> <snip>
>> Boot from a live CD using the CentOS 6.2 install media. Once booted:
>>
>> <bash># grub
>> <grub> root (hd0,0)
>> <grub> setup (hd0)
>> <grub> root (hd1,0)
>> <grub> setup (hd1)
>> <grub> root (hd2,0)
>> <grub> setup (hd2)
>> <grub> quit
>> <bash># reboot
>>
>> This assumes that grub sees the drives at '0, 1 and 2' and the boot
>> partition is the first on each drive. If it is, when you type 'root
>> (hdX,0)' it should report that a file system was found. The 'setup
>> (hdX)' will tell grub to write the MBR to the specified disk.
> THANK YOU! I could have used that once or twice, and had no idea that grub
> could create a std. MBR.

When I set up a RAID 1, I do it like this:

device (hd0) /dev/sda
root (hd0,0)
setup (hd0)
device (hd0) /dev/sdb
root (hd0,0)
setup (hd0)
device (hd0) /dev/sdc
root (hd0,0)
setup (hd0)

This way, all the drives are set up as if they are hd0.  This way, any
of them will boot normally as a stand-alone drive.

-- 
Bowie


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