Re: Grub-install fails with grub-install: error: disk `md0' not found.

[Mark Syms]

Fixed if myself.

Turns out that an earlier package run (some two weeks ago) had removed
mdadm and I hadn't spotted that. So when grub-install tried to
interrogate the raid it didn't have any user space tools to do so.

Error message whilst sort of accurate wasn't actually that helpful,
saying "no mdadm found" would have immediately pointed the finger.

Thanks for the help Pascal.

Mark.

On 1 April 2018 at 12:54, Mark Syms <address@hidden> wrote:
> Inline below. Thanks for the help.
>
> On Sun, 1 Apr 2018 at 12:41 Pascal Hambourg <address@hidden> wrote:
>>
>> Le 31/03/2018 à 12:13, Mark Syms a écrit :
>> >
>> > My system received a package update for grub from the distribution but
>> > as the package completed its update it failed (on all four drives)
>> > with the error in the subject line.
>>
>> Which distribution ?
>
> Ubuntu server 16.04.4 LTS (originally installed as 11.10 and upgraded
> to LTS releases). System has been running since early 2012 with no
> issues up to the recent package upgrade. It's not a problem with
> setting it up, I did tat years ago and I'm quite happy that I
> understand the process, its just gone wrong as part of the upgrade.
>
>> Can you post the full command line and output (without -v), along with
>> the full output of cat /proc/mdstat and fdisk -l (on one disk) ?
>
> # grub-install /dev/sda
> Installing for i386-pc platform.
> grub-install: error: disk `md0' not found.
>
> ------------
>
> # cat /proc/mdstat
> Personalities : [raid1] [raid6] [raid5] [raid4] [linear] [multipath]
> [raid0] [raid10]
> md1 : active raid5 sda3[0] sdc3[2] sdd3[4] sdb3[1]
>       5845172736 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/4] 
> [UUUU]
>
> md0 : active raid1 sda2[0] sdd2[3] sdc2[2] sdb2[1]
>       5118964 blocks super 1.2 [4/4] [UUUU]
>
> unused devices: <none>
>
> -----------------
>
> fdisk (I've included the md devices as well but they probably don't
> give any more than the above)
>
> Disk /dev/sda: 1.8 TiB, 2000398934016 bytes, 3907029168 sectors
> Units: sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 4096 bytes
> I/O size (minimum/optimal): 4096 bytes / 4096 bytes
> Disklabel type: gpt
> Disk identifier: 7CE9A519-9E12-48F6-AE3A-4B2A732BAC67
>
> Device        Start        End    Sectors  Size Type
> /dev/sda1      2048       4095       2048    1M BIOS boot
> /dev/sda2      4096   10244095   10240000  4.9G Linux RAID
> /dev/sda3  10244096 3907028991 3896784896  1.8T Linux RAID
>
>
> Disk /dev/md0: 4.9 GiB, 5241819136 bytes, 10237928 sectors
> Units: sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 4096 bytes
> I/O size (minimum/optimal): 4096 bytes / 4096 bytes
>
>
> Disk /dev/md1: 5.5 TiB, 5985456881664 bytes, 11690345472 sectors
> Units: sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 4096 bytes
> I/O size (minimum/optimal): 524288 bytes / 1572864 bytes