metalus

I have a thin client with 3x m.2 slots connected to a 6x bay JBOD. (ms-01) 1tb m.2 SSD for apadata 2x 500gb m.2 cache pool Looking to keep the setup as quiet as possible. I have no parity or backups in current config. JBOD is running 4x4 4tb sata SSD's with two empty slots. No spinning disks. Small network 12u rack in office. I'm looking to add parity or raw duplication but want to maintain maximum storage and speed. In the remaining bays I'm looking to add standard HDD's since the SSD's are expensive to expand. I'm considering two options and looking for guidance. Just checking theory here. If I snag two cheap 4tb HDDs and run it as dual parity my understanding is my write performance will drop to HDD speeds? Although this will maintain array size and read will still be SSD speeds? HDD will spin up during write but not read? This should be none issue because of the write to cache pool? Considering alternative. I purchase a 16tb HDD and just run raw mirror backup bi-weekly, say early AM. The HDD will only spin up during this process?