The SMS can be configured to operate in a two-node cluster, increasing availability of the SMS server should an unexpected event cause one of the nodes to fail or become inaccessible.

SMS HA Administration Concepts and Planning

The most important aspects of the SMS HA cluster are the heartbeat connection and database replication. Periodically, verify that both activities are performing as expected. If you need to upgrade SMS software or apply an SMS patch, you must break apart the cluster and upgrade, or patch, each of the two SMS HA cluster nodes independently. The reason for this is that one of the nodes is always passive and therefore the SMS software is not fully operational and cannot be upgraded or patched. If you need to perform maintenance on the active SMS server, for example to swap out a network card, you can invoke a failover on the active node, which deactivates it and activates the passive SMS server. Once deactivated you can take the node offline, power it off, and perform maintenance on it.