The difference between dual-standby and dual-machine duplex

Dual-Machine hot standby is now commonly referred to as the Active/standby way, server data, including database data to two or more servers to write, or use a shared storage device. When an Active server fails, the standby machine is activated by software diagnosis (usually through heartbeat diagnostics) to ensure the application is fully restored to normal use in a short period of time.

Two-machine standby, on the basis of hot standby, two relatively independent applications run at the same time on both machines, but each is set to standby, and when one server fails, another server can take over the application of the failed server in a short time, thus ensuring the continuity of the application. This approach is actually a dual-machine hot standby application. It avoids two applications using four servers to implement two-machine hot standby respectively.

Dual-machine duplex, two or more servers are active, at the same time running the same application, to ensure the overall performance, but also to achieve a load balance and mutual backup. Need to leverage disk cabinet storage technology (preferably SAN). For database services, it requires the support of database software, is more complex. The Web server or application server is simpler.