https://askubuntu.com/questions/350266/how-can-i-create-a-raid-array-with-2tb-disks

Firstly, identify the device names for your new hard drives by running sudo fdisk -l. In my case, the new drives were /dev/sdc and /dev/sdd. OR (First to find the drive you want to open, use “ls -l /dev | grep sd” to list drives and their partitions; this is to allow you to see if/which drives are already partitioned. Also use “lsscsi and “lsblk” and “blkid” for different ways to see disk drives and their partitions, or use fdisk -l. Then create the partition on each drive. The partition table needs to be GPT to allow more than 2TB to be used, so you cannot use fdisk.

lsblk is a nice way to display an easy to read disk and partition layout, blkid shows the disks with their UUIDs and file system types.

  1. Run parted /dev/sdc. (or… parted -a optimal /dev/sdc, this is for correct alignment)
  2. At the (parted) prompt, create the partition table by typing mklabel gpt.
  3. Check the free space on the drive by typing print free. In my case, this shows 3001GB.
  4. Create the partition by typing mkpart primary 1M 3001GB. This starts the partition a 1M offset giving a 4096 byte alignment. This may or may not be necessary, but won't hurt if its not. (or… mkpart primary 0% 100% for correct alignment)
  5. Check your partition is set up by typing p. Then type q to quit.
  6. Format the partition with XFS: mkfs.xfs /dev/sdc1
  7. Set the label of the XFS volume: xfs_admin -L newName /dev/sdc1
  8. Create a mount point to use the XFS parition with: mkdir /mnt/eSATA_backup
  9. Run blkid to get the UUID of /dev/sdc1
  10. edit /dev/fstab and add the line: 
  UUID=ebdb9bf5-0312-4f42-829a-ad81b0cd24a3 /mnt/eSATA_backup       xfs     noauto,defaults,noatime 0 0
  11. Now you can use a script to mount it when a backup is being run and unmount it after it's done so issues such as failed device on reboot won't hang the machine.
  12. Add info on possible script option for automount and unmount as a part of a backup routine.