Upgrade Disks on My Cloud EX2

My Cloud OS 3 Personal & Network Attached Storage My Cloud EX2
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OK, so I want to replace my 3 TB x 2 raid 1 pair with 6 TB x 2 raid 1 pair. Could I:

  1. pull one of the existing 3 TB drives, reformat it for windows and then copy the data from the other 3 TB drive to the windows 3 TB drive.
  2. install the two 6 TB drives, build a raid 1 array.
  3. copy the data back from the “windows” drive to the Mycloud EX2.
    ???
    Other option, can I read a single volume of the 3TB raid 1 array on a Linux boot?