I bought a secondhand 6-bay for around 100 euro and put openwrt on it, mdadm is perfect for the job. Check whether the system is easy to root beforehand. I had

I bought a secondhand 6-bay for around 100 euro and put openwrt on it, mdadm is perfect for the job. Check whether the system is easy to root beforehand. I had to do it via a hardware serial connection on the motherboard.