Installing grub2 fails due to labels conflicts?

Question

I had a working arch setup on /dev/sda with the following setup:
/dev/sda1 /boot
/dev/sda4 /
Then I bought a new disk and installed a new archlinux onto LUKS from the previous working system. The new setup is the following:
/dev/sdb1 /boot
/dev/sdb2 /dev/mapper/cryptroot /
However I'm still booting from the old sda1 grub-legacy, I just edited the menu.lst to point to the new sdb1 /boot. Now I want to wipe the old disk because I want to encrypt it too. So I installed grub and issued the command:
root@HomeC # grub-install /dev/sdb
Installing for i386-pc platform.
grub-install: warning: Attempting to install GRUB to a disk with multiple partition labels. This is not supported yet..
grub-install: 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..
grub-install: error: will not proceed with blocklists.
I don't know it there are multiple labels or not, and my google-fu didn't reveal anything useful (tried this for example: http://slopjong.de/2013/10/11/attemptin … n-labels/). My labels are like this:
lrwxrwxrwx 1 root root 10 2014-03-24 10:43 bakoboot -> ../../sdb1
lrwxrwxrwx 1 root root 9 2014-03-24 11:16 bakodisk -> ../../sdb
lrwxrwxrwx 1 root root 10 2014-03-24 10:43 sda1boot -> ../../sda1
lrwxrwxrwx 1 root root 10 2014-03-24 10:43 sda4ext4 -> ../../sda4
Well there is a suspicious entry, because I don't know how I labelled sdb itself as bakodisk, I probably wanted to label sdb2. Could that be the issue? How do I solve this problem? Also I tried to remove the label with
e2label /dev/sdb ""
but that didn't help either.

Answer 1

Maybe worth quoting the result of fdisk -l:
Disk /dev/sda: 298,1 GiB, 320072933376 bytes, 625142448 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: 0x00091306
Device Boot Start End Blocks Id System
/dev/sda1 * 63 6256639 3128288+ 83 Linux
/dev/sda2 619080840 625137344 3028252+ 5 Extended
/dev/sda4 6256640 619079679 306411520 83 Linux
/dev/sda5 619080903 625137344 3028221 82 Linux swap / Solaris
Partition table entries are not in disk order.
Disk /dev/sdb: 232,9 GiB, 250059350016 bytes, 488397168 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: 0xc54cfa1d
Device Boot Start End Blocks Id System
/dev/sdb1 2048 2099199 1048576 83 Linux
/dev/sdb2 2099200 488397167 243148984 83 Linux
Disk /dev/mapper/cryptroot: 231,9 GiB, 248982462464 bytes, 486293872 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