grub2 boot failure when adding disks

[Alex Regan]

Hi,

I'm having trouble reinstalling grub on a fedora20 system after adding 
two new disks in addition to the two that are already installed. It 
appears to install correctly, but after booting, only a single dot then 
a flashing cursor is printed.

There are currently two RAID1 disks mirrored using mdadm mounted on / 
and /boot, and I'm attempting to add two more to be mounted separately 
on /var.

If I remove the new two disks I just installed the system boots normally.

My fstab after adding the new md2 partition for /var looks like this:

UUID=3c2510e3-1d30-4c5a-be1b-5639732acea8 /                       ext4 
   defaults        1 1
UUID=0c3a3ce6-dac9-4b8c-8836-4f086272427f /boot                   ext4 
   defaults        1 2
UUID=916747c5-3043-4ad6-9a6f-6e688bb0a731 swap                    swap 
   defaults        0 0
UUID=7e39732f-8080-4869-b218-4e45eada381e swap                    swap 
   defaults        0 0
/dev/md2                                  /var                    ext4 
   defaults        0 0

My /proc/mdstat looks like this:

# cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] 
[raid4] [raid10]
md1 : active raid1 sda2[0] sdc2[1]
       51198904 blocks super 1.2 [2/2] [UU]
       bitmap: 1/1 pages [4KB], 65536KB chunk

md0 : active raid1 sda1[0] sdc1[1]
       511988 blocks super 1.0 [2/2] [UU]

md2 : active raid1 sdb1[0] sdd1[1]
       58581824 blocks super 1.2 [2/2] [UU]

Installing grub2 on sda appears to work but doesn't boot:

# grub2-install /dev/sda
Installation finished. No error reported.

I recalled installing the boot sector on md1 (on /) during installation, 
but that doesn't work at all. I believe

# grub2-install /dev/md1
/usr/sbin/grub2-bios-setup: warning: File system ‘ext2’ doesn't support 
embedding.
/usr/sbin/grub2-bios-setup: warning: Embedding is not possible.  GRUB 
can only be installed in this setup by using blocklists.  However, 
blocklists are UNRELIABLE and their use is discouraged..
/usr/sbin/grub2-bios-setup: error: will not proceed with blocklists.

Booting from the sysrescuecd to the two existing disks works fine. Below 
is my fdisk output.

Disk /dev/sdb: 55.9 GiB, 60022480896 bytes, 117231408 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x4255c226

Device    Boot Start       End   Blocks  Id System
/dev/sdb1       2048 117231407 58614680  fd Linux raid autodetect


Disk /dev/sdc: 55.9 GiB, 60022480896 bytes, 117231408 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x00079691

Device    Boot     Start       End   Blocks  Id System
/dev/sdc1 *         2048   1026047   512000  fd Linux raid autodetect
/dev/sdc2        1026048 103426047 51200000  fd Linux raid autodetect
/dev/sdc3      103426048 117229567  6901760  82 Linux swap / Solaris


Disk /dev/sdd: 55.9 GiB, 60022480896 bytes, 117231408 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x3d870e51

Device    Boot Start       End   Blocks  Id System
/dev/sdd1       2048 117231407 58614680  fd Linux raid autodetect


Disk /dev/sda: 55.9 GiB, 60022480896 bytes, 117231408 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x00013cd6

Device    Boot     Start       End   Blocks  Id System
/dev/sda1 *         2048   1026047   512000  fd Linux raid autodetect
/dev/sda2        1026048 103426047 51200000  fd Linux raid autodetect
/dev/sda3      103426048 117229567  6901760  82 Linux swap / Solaris


Disk /dev/md2: 55.9 GiB, 59987787776 bytes, 117163648 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk /dev/md0: 500 MiB, 524275712 bytes, 1023976 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk /dev/md1: 48.8 GiB, 52427677696 bytes, 102397808 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

Thanks for any ideas.
Alex