What Is HA and Why Is HA Required?

HA refers to high availability. The SAP system architecture consists of three layers: application server, message server, and database. SAP best practices recommend distributed deployment, which enables high availability of different servers.

• Application server HA: In active-active mode, if one application server breaks down, the other server still works normally, ensuring no service interruption. SAP application servers are usually deployed in a cluster. In addition to HA, this deployment mode also balances workloads.
• Message server HA: In active-standby mode, the message server distributes user requests to application servers. The HA software of the operating system is required to support the switchover of shared resources.
• Database HA: In active-standby mode, if the active database breaks down, upper-layer applications automatically connect to the standby database, ensuring no service interruption.

For small- and medium-sized enterprises, select two application servers to both deploy message server components. Adopt the HA architecture to your SAP production system.