Partition is created and grub is installed as instructed in the thread.
Also Grub is installed now.
should i make any config changes ( or not )in the /boot/grub/ directory?
Number Start (sector) End (sector) Size Code Name
1 2048 7813119 3.7 GiB FD00 Linux RAID
2 34 2047 1007.0 KiB EF02 BIOS boot partition
3 27344896 1980469247 931.3 GiB FD00 Linux RAID
4 1980469248 2930276351 452.9 GiB FD00 Linux RAID
5 7815168 27344895 9.3 GiB FD00 Linux RAID
root@nasbox:~# grub-install /dev/sdb
Installation finished. No error reported.