When configuring RAID it’s quite important to have the same partition tables on every disk. I’v done this many times on msdos partition tables like this:
sfdisk -d /dev/sda | sfdisk /dev/sdb
but it’s not working any more on GPT partition tables.
But it still can be done but with different toolstack 🙂
apt-get install -y gdisk
Then use sgdisk like this:
sgdisk -R /dev/sd_dest /dev/sd_src sgdisk -G /dev/sd_dest
First command will copy partition from /dev/sd_src to /dev/sd_dest. Second will randomize partition UUID’s – needed only if you want to use disks in same machine (this is my case).