Comment 4 for bug 2047764

The raft backend is only supported on the 1.8 channel or newer, but it is the default. From the README for the charm:

> If no databases are related, vault will be auto configured to use
> its embedded raft storage backend for storage and HA.
> Note that raft storage is only supported in Vault 1.8/stable or newer
> (see `channel` in charm config).

Thus, no psql or mysql backends would default back to raft for a 1.8 or newer charm.

> Maybe vault service should be stopped and db config should be removed from config file if db relation is removed?

Yes, this is what I said in #1. My concern is that a newer charm may revert to raft; however, if the service is stopped across all units then re-adding a different shared-db would then not be a problem.