Re: grub2-install failing after RAID 1 HDD replaced

[Andrei Borzenkov]

On Tue, Mar 22, 2016 at 1:10 PM, Kilburn Abrahams <address@hidden> wrote:
> I upgraded a gentoo box which has RAID 1 from 350GB to 1TB drives. Then I
> decided to upgarde from grub 1 to grub 2.
> Steps:
> 1.  installed grub 2 V2.02 beta 2
> 2.  checked /boot/grub/device.map (all looked fine)
>      (fd0) /dev/fd0
>      (hd0) /dev/sda
>      (hd1) /dev/sdb

device.map is mostly redundant in case of grub2 except in very special
use cases. You are almost always better off without it. Certainly it
is not required in your case.

> 3.  grub2-install --grub-setup=/bin/true /dev/sda

--grub-setup is obsolete, use --no-bootsector instead. But you are
aware that it won't install boot sector/core.img, so you will need
some other bootloader to chainload it, are not you?

>      Installing for i386-pc platform.
>      grub2-install: error: disk `mduuid/c845d9551ec0b439cb201669f728008a'
> not found.
>
> blkid is returning this.
>
> /dev/md0: UUID="b75a81b5-59c6-4eb8-aadc-66650f5ea1bd" TYPE="ext2"
> /dev/md2: UUID="3211adef-bf44-41d4-86bb-164b46c3d909" TYPE="ext4"
> /dev/md1: UUID="6036ef9a-878e-45ce-b5b3-bec8cd920fd2" TYPE="swap"
> /dev/sdb1: UUID="c845d955-1ec0-b439-cb20-1669f728008a"
> TYPE="linux_raid_member" PARTUUID="6795d2bc-01"
> /dev/sdb2: UUID="e1c7ed62-0e38-d06b-cb20-1669f728008a"
> TYPE="linux_raid_member" PARTUUID="6795d2bc-02"
> /dev/sdb3: UUID="18a2e9e5-05d5-4ba4-cb20-1669f728008a"
> TYPE="linux_raid_member" PARTUUID="6795d2bc-03"
> /dev/sda1: UUID="c845d955-1ec0-b439-cb20-1669f728008a"
> TYPE="linux_raid_member" PARTUUID="6795d2bc-01"
> /dev/sda2: UUID="e1c7ed62-0e38-d06b-cb20-1669f728008a"
> TYPE="linux_raid_member" PARTUUID="6795d2bc-02"
> /dev/sda3: UUID="18a2e9e5-05d5-4ba4-cb20-1669f728008a"
> TYPE="linux_raid_member" PARTUUID="6795d2bc-03"
>

Well, something went wrong, it should not interpret device UUID as MD
UUID. Where is your /boot located?

> The HDD are formatted as
> /dev/sda1 * 2048 67583 65536 32M fd Linux raid autodetect
> /dev/sda2 67584 12355583 12288000 5.9G fd Linux raid autodetect
> /dev/sda3 12355584 1953525167 1941169584 925.6G fd Linux raid autodetect
> /dev/sdb1 * 2048 67583 65536 32M fd Linux raid autodetect
> /dev/sdb2 67584 12355583 12288000 5.9G fd Linux raid autodetect
> /dev/sdb3 12355584 1953525167 1941169584 925.6G fd Linux raid autodetect
>
> Is there something I am missing? I am using mdadm 3.3.1 but can upgarde to
> 3.4. I believe grub2-install calls mdadm via grub2-probe, is this what is
> causing the problem, if so, how can I correct this?
>

I suggest you retest with 2.02~beta3 and if problem still persists we
can try to debug it. You can find all pre-releases on
http://alpha.gnu.org/gnu/grub.