From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Peter Sangas" <pete@wnsdev.com>
Subject: GRUB warning after replacing disk drive in RAID1
Date: Mon, 27 Feb 2017 15:37:24 -0800
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Hi all.

I have a RAID1 with 3 disks sda,sdb,sdc.  After replacing sdc and re-syncing
it to the array I issued the following command to load grub but I get this 
warning:

grub-install /dev/sdc

Installing for i386-pc platform.
grub-install: warning: Couldn't find physical volume `(null)'. Some modules
may be missing from core image..
grub-install: warning: Couldn't find physical volume `(null)'. Some modules
may be missing from core image..
Installation finished. No error reported.

Does anyone know why I get this warning and how to avoid it.

uname -a 
Linux green 4.4.0-47-generic #68-Ubuntu SMP Wed Oct 26 19:39:52 UTC 2016
x86_64 x86_64 x86_64 GNU/Linux

mdadm -V
mdadm - v3.3 - 3rd September 2013


Thanks,
Pete