Comment # 3 on bug 960517 from Jiri Srain

I think that the file explains your behavior, especially in contrast with

grub2-install /dev/sda

you mentioned above.

My assumption as that after installation, MBR was occupied with the generic
code, which loads boot sector of the partition with the active flag, and this
boot sector contained GRUB.

Then, from some reason, you ran grub2-install /dev/sda for the first time,
which replaced the generic code in MBR with GRUB, however, you did not change
the configuration file.

Then, when GRUB got upgraded, it updated itself in the boot sector (according
to the configuration file), but since there is no update of the generic MBR
code, there was no need to update it.

However, since you ran grub2-install /dev/sda, the code in MBR pointed to stuff
which belonged to GRUB version you just removed.

Detecting this is not really possible - even if there is GRUB code in MBR, it
may belong to other instance of GRUB on the same machine, which chainloads your
system, and therefore reinstalling it would break such set-ups.

I think that you should either adjust GRUB configuration file to install to MBR
on next update, or restore the generic booting code in your MBR. Then, I
believe, GRUB updates should work for you.


Michael, did I miss anything?