Not all storage backends support high availability mode for Vault. Only the storage backends that
support locking can enable Vault to run in a multi-server mode where one server is active and the
others are standby. Some examples of storage backends that support high availability mode are
Consul, Integrated Storage, and ZooKeeper. Some examples of storage backends that do not support
high availability mode are Filesystem, MySQL, and PostgreSQL. Reference:
https://developer.hashicorp.com/vault/docs/concepts/ha1,
https://developer.hashicorp.com/vault/docs/configuration/storage2
