I need ActiveMQ Artemis broker to be started in a zero persistence mode and then move to use persistence once the storage volume is available. Is there any smarter way of doing this than starting while referencing a broker.xml defining a zero persistence and then restarting while passing a path to the different broker.xml configuring persistence? I also see that touching broker.xml reloads configuration, but it's not clear to me if persistence can be managed this way without a hard restart.
You will need to restart the broker if you want to move from a non-persistent configuration to a persistent configuration. The persistence configuration can't be changed at runtime.
See the documentation for more details on what is eligible to be changed in broker.xml at runtime.