I believe we are deprecating the dbHash functionality as of 3.2, given that we are switching to the replica set architecture for the config database.

Although replica sets are designed to have [eventual] consistency among their nodes, inconsistencies in the config db can render a sharded cluster unusable. Thus it seems reasonable to implement additional validation mechanism(s) in the unlikely event of consistency issues. For example, we could periodically check the consistency of config repl set members.