Stateless Mode and High Availability
By default, Schema Registry does not have server-side caching. Each time a client sends a query, the client reads the data directly from the database.
The lack of server-side caching creates a minor performance impact. However, it enables Schema Registry to be stateless and be distributed over multiple hosts. All hosts will use the same database. This enables a client to insert a schema on host A and query the same schema on host B.
You can store JAR files similarly in HDFS and retrieve a file even if one of the hosts is down.
To make Schema Registry highly available in this setup, include a load balancer on top of the services. Clients will communicate through the load balancer. The load balancer will then determine which host to send the requests to. If one host is down, the request is sent to another host. In CDP, the load balancer is Apache Knox.