If I understand correctly,
RAID 1 is two drive that mirror each other, and if one fails, it can be replaced and some hours later, it's a mirror of the good drive.
Raid 0 combines 2 drives in a way that offers a speed (access) boost, but spreads data over 2 drives that can then no longer be split, i.e. you have one bigger drive with performance boost.
Can the two be combined? 4 drives, 3TB each set as two RAID 0 pairs that mirror via RAID 1. I understand that a failure then means two drives need to be pulled and replaced to rebuild the set.