I am the author and maintainer of The Multiplexed File System.
muxfs is a mirroring, checksumming, and self-healing filesystem layer for OpenBSD. It mirrors a filesystem tree across a series of directories, and employs checksum databases to validate and restore files automatically.
HN front page 2022-08-14, link in article. A filesystem to multiplex file I/O into multiple directories with checksums to check and restore data automatically.