Re: Re: grub2-install: Couldn't find physical volume ‘(null)’.

[Andrei Borzenkov]

On Mon, Apr 11, 2016 at 1:56 PM, Sam Varshavchik <address@hidden> wrote:
>> > address@hidden ~]# /sbin/grub2-install /dev/sdb
>> > Installing for i386-pc platform.
>> > /sbin/grub2-install: warning: Couldn't find physical volume ‘(null)’.
>> > Some modules may be missing from core image..
>> > /sbin/grub2-install: warning: Couldn't find physical volume ‘(null)’.
>> > Some modules may be missing from core image..
>> > Installation finished. No error reported.
>> >
>> > Now, anyone have any idea what's up with these warnings?
>> >
...
>
> Googling around finds some references of this warning coming out while the
> md-raid volumes are being synced. This warning still comes out after
> everything is fully synced up.
>

I think I know what happens. Did you reboot after MD was resynced? If
not, please try

blockdev --flushbufs /dev/sda
blockdev --flushbufs /dev/sdb

and try grub2-install once again.