High availability databases generally fall into two categories, with a third category becoming more common:
Active-passive databases: Where a database has an active node that processes requests with a hot spare that is ready to go in a disaster
Active-active databases: Where a database has active nodes that shard data and perform writes to the database
Multi-active databases: Where a database has at least three active nodes, each of which can perform reads and writes for any data in the cluster without generating conflicts.