grub fails to boot, prints only a single dot

[Alex Regan]

Hi,

I have a fedora20 system on a 1U rackmount Supermicro chassis with two 
disks in a mdadm RAID1 configuration that's been running for quite some 
time. I recently added two additional disks, in a separate RAID1, and 
mounted it on /var.

After adding the two new disks, the system failed to boot. No grub boot 
menu or anything. Just a single dot then a newline, where the system 
would sit there until I eventually had to hard reset it to boot.

Removing the two new disks and the system boots again normally (except 
for the new /var mountpoint, of course).

Running grub2-install again for all four disks doesn't help. I've even 
uninstalled and reinstalled the kernel, and tried to manually regenerate 
the initramfs with no change.

Does anyone understand grub enough to help troubleshoot this? I suspect 
it's something to do with the second-stage loader?

Thanks,
Alex