# Dual State Failover

An unshared state connection factory can include shared-state server pairs in its list of backup servers. When both shared state and unshared state servers are included, the failover process is a combination of both types of failover.

The following image illustrates the dual state failover process.

In this example, servers A1 and A2 share state. Servers B1 and B2 also share state. However, A1 and A2 do not share state with B1 and B2.

The EMS clients created connections using a connection factory with A1, A2 + B1, B2. The initial server connections were with server A1. When the connection to A1 failed, the failover process proceeded as described in Shared State Failover Process, and the clients connect to A2.

A2 then failed, before A1 restarted. The clients next created connections to B1, recreating all runtime objects from the connection (as described above in Unshared State Failover Process). B1 is now the active server. Because B1 and B2 share state, If B1 fails, B2 becomes the active server.

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