Re: GRUB2, GPT, mdadm & LVM

[Andrey Borzenkov]

В Thu, 18 Jul 2013 13:56:21 +0200
Sander Smeenk <address@hidden> пишет:

> Hi,
> 
> I'm having issues getting GRUB to boot from my setup. It drops to an
> rescue shell stating it can't find the LVM root for my system. Similar
> 'stacked' setups (md raid5/6 lvm, root on lvm) work fine: difference
> seems to be GPT.
> 
> Setup is:
> 16x 3TB disks with GPT partitions:
> | 1   2048         4095   1024.0 KiB  EF02  BIOS boot partition
> | 2   4096   5860533134   2.7 TiB     FD00  Linux RAID
> 
> Next i created an mdadm /dev/md0 with raid6:
> | md0 : active raid6 sda2[0]  [ .. ]  sdp2[2]
> |  41021865472 blocks super 1.2 level 6, 64k chunk, algorithm 2 [16/16] 
> [UUUUUUUUUUUUUUUU]
> |  [==>..................]  resync = 10.1% (296747044/2930133248) 
> finish=985.3min speed=44540K/sec
> 
> The entire /dev/md0 is a Physical Volume for LVM on which two Logical
> Volumes were created, one for / and one for swap. This setup works just
> fine when activated from within a LiveCD like GRML:
> | # lvdisplay | grep "LV Name"
> |   LV Name                host_root
> |   LV Name                host_swap
> |
> | # mount /dev/mapper/fdi-host_root /tgt
> |
> | # ls /tgt/boot/
> | System.map-3.8.0-26-generic  abi-3.8.0-26-generic config-3.8.0-26-generic
> | grub/  initrd.img-3.8.0-26-generic vmlinuz-3.8.0-26-generic
> 
> 
> During installation no errors are logged. GRUB embeds fine in the BIOS
> boot partition and the generated grub.cfg shows 'insmod lvm' and 'insmod
> raid6rec' amongst others. The BIOS starts GRUB just fine, it's GRUB
> where it seems to fail:
> 
> 
> During boot, GRUB starts and drops to 'grub rescue>' stating "Error:
> disk lvm/fdi-host_root not found". Typing 'ls' in the rescue shell shows
> the '(md/0)' device, but LVM is never started by GRUB.
> Much more than 'ls' isn't available in the rescue shell. Typing 'insmod
> lvm' just returns without error, typing 'insmod thisdoesnotexist'
> complains GRUB can't find the disk 'lvm/fdi-host_root'.
> 
> 
> Could someone please advise where i am going wrong?
> 
> 
> I tried (re)creating the core.img like so:
> | # grub-mkimage -o /boot/grub/core_lvm.img -O i386-pc \
> |     part_gpt part_msdos mdraid09 mdraid1x raid6rec \
> |     diskfilter lvm ext2
> 

Your image is lacking physical disk driver. This will be biosdisk on PC
BIOS platform.

> And put that in all the disks:
> | # grub-bios-setup -b i386-pc/boot.img -c core_lvm.img /dev/sdX
> 
> Alas, to no avail.
> 
> 
> Thanks!
> -Sndr