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

[Sam Varshavchik]

grub 2.02, Fedora x86-64.

I have /dev/sda and /dev/sdb in a RAID-1 configuration. This is the Linux  
kernel's md-raid driver.

/dev/sda started failing SMART.

I ran /sbin/grub2-install /dev/sdb. My recollection is that it ran without  
any complaints.

After that, I yanked out /dev/sda. I reattached /dev/sdb as /dev/sda, and  
put in a new hard drive as the new /dev/sdb.

I booted up, and kicked off a rebuild of my RAID-1 volumes, everything is  
going well.

Now, after all of that was done, I decided to install grub2 on the new  
/dev/sdb:

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?

More importantly, should I dare to run /sbin/grub2-install /dev/sda, just to  
make sure everything is nicely in sync?

P.S., currently I still have one raid volume syncing, but this does not  
appear relevant.

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