The following description of system and application high availability HA, what is correct?

High availability improves the availability of systems and applications by minimizing downtime caused by routine maintenance operations (planned) and sudden system crashes (unplanned).

B. The deployment mode of high-availability architecture mainly includes active backup, active-active, and disaster recovery

HA system is currently the most effective means for enterprises to prevent the core computer system from being shut down due to failure

D. High availability technology can automatically detect server node and service process errors, failures, and automatically reconfigure the system appropriately when this occurs