[SATLUG] GRUB @ RAID

dikov dikov dikov1 at yahoo.com
Wed Oct 16 19:25:11 CDT 2013


Hi all, sorry for the pause with reply. 

Now as i restored grub with live CD GUI I am checking grub config in order to get what might that be a problem.
Sure I tried genberal steps: 

grub> find /grub/stage1
(hd0,0)
(hd1,0)

root (hd0,0)
Filesystem type is ext2fs, partition type 0x83

setup (hd0)
Checking if "/boot/grub/stage1" exists... no
Checking if "/grub/stage1" exists... yes
Checking if "/grub/stage2" exists... yes
Checking if "/grub/e2fs_stage1_5" exists... yes
Running "embed /grub/e2fs_stage1_5 (hd0)"... 27 sectors are embedded. 
suceesd
Running "install /grub/stage1 (hd0) (hd0)1+27 p (hd0,0)/grub/stage2 /grub/grub.conf"... failed
Error 22t: No such partition



As I understand that the problem is that grub in "find /grub/stage1" finds the two real hard drives involved into RAID1 but should find the "raided" drive i.e. /dev/mapper/dff1_XXX
When I installed from GUI I pointed to the MBR of the "raided" drive dff1_XXX and grub was restored.
device.map also has only one entry 
(hd0) /dev/mapper/dff1_XXXX

So the question is how to let grub to see "raided" drive. Am I right?

Dmytro




On Saturday, October 12, 2013 11:10 PM, Daniel Wallace <danielwallace at gtmanfred.com> wrote:
 


> Date: Sat, 12
 Oct 2013 18:36:30 -0700
> From: dikov1 at yahoo.com
> To: satlug at satlug.org
> Subject: [SATLUG] GRUB @ RAID
> 
> Hi
> There is an Centos 6 installation with two HDDs in LSI RAID1 array. /boot is on separate partition 1 and rest (/) on LVM. After yum update with new kernel the boot process stopped at grub with error 13. Here I was asked to help. I tried to install grub into MBR of the RAID1 disk manually. I booted from rescue live CD and from chroot tried to 
> 
> #grub-install   /dev/mapper/ddf1_XXXXXX (i.. to MBR of RAID)
> 
> but got
 error that there is corresponding BIOS drive. I spent a lot
 of time in grub  console no luck. With soft RAID I should install into MBR of every disk like 
> 
> grub> setup (hd0)
> but this did not work here.
> 
> Finally, I followed "install or upgrade" in live CD menu and was able to restore grub without reinstalling OS. In that wizard I selected to install GRUB in MBR of the RAID drive i.e. ddf1_XXXX and it worked.
> So my question is what the magic going on with grub and hard RAID? 
> best,
> Dmytro
> 
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did you remember to set your

grub> root (hd0,0) before running setup (hd0) ? you also may need to set device (hd0) /dev/mapper/ddf1_XXXX  before anything else

or if you don't want to set device, you can should be able to find what to set root to with

grub> find /grub/stage1

- Daniel

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