Thanks Arno, Pascal and Gary with your input i manage to copy the partition to new drive in GPT format and my all drives (mdadm devices) are synced now.
I have 4 RAID1 Partitions for all for different purpose.
md1 : active raid1 sdb5[2] sda5[0]
9763768 blocks super 1.2 [2/2] [UU]
md3 : active raid1 sdb4[2] sda4[0]
474902392 blocks super 1.2 [2/2] [UU]
md2 : active raid1 sdb3[2] sda3[0]
976561016 blocks super 1.2 [2/2] [UU]
md0 : active raid1 sdb1[2] sda1[0]
3904500 blocks super 1.2 [2/2] [UU]
but there are few confusions. actually in my old drive. there was a extended partition for SWAP. however when i copy the partition table with gdisk "x" and "u" option it created the file successfully however. i can not see extended in the output. gdisk -l /dev/sdb
Number Start (sector) End (sector) Size Code Name
1 2048 7813119 3.7 GiB FD00 Linux RAID
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
number "5" is the swap partition as i know it from size. and i also attached that partition to my mdadm drive md1 which was set to swap by me and it is successfully synced. now my question is as i can not see the extended partition type in the list by attaching "5" partition to the swap directory. have i done it the right way thing or i have done it wrong?
my last question is making the new 2TB drive able to boot.
when i run the command grup-install it gives me error.
# grub-install /dev/sdb
/usr/sbin/grub-setup: warn: This GPT partition label has no BIOS Boot Partition; embedding won't be possible!.
/usr/sbin/grub-setup: error: embedding is not possible, but this is required when the root device is on a RAID array or LVM volume.
if i change the type to "ef02" (Bios Boot Partition) i may not be able to attach that partition to my current raid level. this is what i think i haven't don't hit and trial technique as i am working on production server.
can you guys please share how can i make the new drive bootable?
your guidance will be highly appreciated in this regard.