Comment by abtinf

Replication increases risk of data loss when implemented incorrectly, because added resources increase the probability of bit errors. This applies to both replicated disks (RAID) and servers. Replicated servers must use ECC memory as well as checksum blocks and periodically scrub data to ensure integrity (e.g. what ZFS does for you). If they don't then a bit error corrupts the data on all servers, because you have no way of know which copies are pristine or how to piece together pristine parts.