Yea, this was one of my disappointments about raid as well. ZFS, on the other hand, stores the hash of every block separately from the block itself, and then u

Yea, this was one of my disappointments about raid as well. ZFS, on the other hand, stores the hash of every block separately from the block itself, and then uses those hashes to check every read. So it only reads the block from a single disk, but it hashes the read block and compares it against the expected hash. If there is an error of any kind the hashes won’t match and ZFS will increment the error counter for the drive and pool. It then examines the other mirrors to find the correct data. Once it has the correct data it overwrites the incorrect block.