Hello @ske5074 ,
Welcome to the forum!
We do not store multiple copies since v3 is started, we use erasure coding, see
and
The RAID is an expensive option, it’s better to run several nodes, each on own HDD. This will result working as a RAID, because all nodes in one location (in the same /24 subnet of Public IPs) are treated as a one big node. So, if one disk die, you will lost only one part of the common data, but not all as in case of one node and bitrot during RAID rebuild.
See also RAID vs No RAID choice