First - there are options to have a DR copy of the ActiveMQ database.
- Let the infrastructure handle it - shared disk does not need to be single point of failure and can be replicated/mirrored on storage level. Depends on your infra tech stack though.
- LevelDB can be replicated among several nodes - hence does not require a shared storage
Anyhow - Artemis is probably the best way forward.
There is no official migration path from AMQ5 to Artemis, but most features in AMQ can be found one way or another in Artemis. Clients should work ootb as well. In the end - it depends on how much custom configuration you're using. Try ask a specific question if you hit any obstacle in migration and you will likely get help sorting that out.