The cache-fs serves as a binary cache that uses LRU (Least Recently Used) as its cleanup protocol. This can improve Artifactory's performance since frequent requests will be served from the cache-fs (as in the case of the S3 binary provider).
The cache-fs binary provider will be the closest filestore layer of Artifactory. This means that if the filestore is mounted, we would like the cache-fs to be local on the artifactory server itself (if the filestore is local, then cache-fs is meaningless). In the case of an HA configuration, the cache-fs will be mounted and the recommendation is for each node to have its own cache-fs layer.