Re: Grub, Raid, LVM
On Sat, Nov 9, 2013 at 9:05 PM, PaulNM <debian@paulscrap.com> wrote:
>
> I've been dealing with a frustratingly vexing issue for a while, and am
> at a loss on where to go next.
>
> Basically, We have a 8x 3TB drive system that I'm trying to install
> Wheezy on. During the install each drive is partitioned with a 1MB BIOS
> Boot partition, followed by a RAID partition taking up the rest of the
> space. The 8 RAID partitions are made into a RAID6 array (8 active, 0
> spare), which is used for a volume group. Two logical volumes (for now)
> are in there, for / and swap. (/ is ext4)
>
> When ever I try to boot the system, I'm stuck at the grub rescue prompt
> after Grub spits out "error: no such disk.". Doing ls shows all eight
> drives (hd0) as well as their associated partitions (hd3,gpt2). Unlike
> the multiple VMs of this setup that I've created on my laptop, there are
> no (md) or (Logical-Volume-Name) entries. Prefix and Root are set to
> (LV-OS), and attempts to set them to other values fail.
>
> I've also attempted an identical install, but with a 200MB Raid
> partition as the second partition, RAID1'd with ext2 /boot. No
> difference. (Actually, the installer fails to use it. I've manually
> copied the files and edited fstab. Updating/reinstalling grub afterwards
> gets the same result.)
>
> Every VM I've created works with no problems, but it always fails on
> the actual hardware. Every theory I can come up with should also fail on
> the VMs. Is there a way to make sure the bios boot partition is being
> used? Would the fact that the physical install puts the usb drive as sda
> be an issue? I've tried editing device.map and updating/reinstalling
> grub, but no dice.
>
> It seems to me that for some reason Grub can't get to it's raid related
> modules. I've checked /boot/grub/grub.cfg. The auto-generated file does
> contain all the insmod lines for raid, raid6rec,mdraid1x, lvm, a bunch
> of part_gpt, and ext2.
1) Did you install grub on all the drives?
2) At the grub prompt, does "lsmod" list lvm, mdraid*, and raid*? If
the output goes off-screen, you'll need to run "set pager=1" first.
3) Boot from a Debian installation cd into rescue mode or from a live
cd (and install mdadm and lvm2), download bootinfoscript, and run it.
RESULTS.txt should give you a better idea of where grub is installed,
etc. Run grub-probe while chrooted; it should also tell you whether
grub is detecting your disks, partitions, raid volumes, and LVM
volumes.
3) Re-install grub with 'grub-install --modules "space-separated list
of lvm and raid modules" /dev/sdX', although it shouldn't be necessary
to ask grub-install to preload a module because AIUI grub-install
determines automatically what modules to include in core.img. Too bad
there isn't a grub utility to determine which modules are included in
this image. There's also a GRUB_PRELOAD_MODULES variable that you can
set in "/etc/default/grub" and the included modules will be loaded as
early as possible; you might want to try that first. (I've never used
this variable.)
Reply to: