I've got an Ubuntu media server with 4 ext4 2TB drives, 1 ext4 4TB drive, and 1 new blank 4TB drive. The ext4 volumes are configured as individual drives (not RAID, etc.). The 2TB drives are about 70% full and the 4TB drive is about 50% full.
I'd like to convert them all to a shared ZFS pool for the drive failure/bitrot protection it offers. My questions are: Can I do that one disk at a time (format the empty as ZFS, move the data from the ext4 4TB to the ZFS 4TB, then add the now-empty ext4 4TB drive to the pool, then move the data from one of the 2TB drives over and add that disk to the pool, etc. Is that possible? And what configuration would people recommend for this? RAID-Z?