Learn concepts related to Vocera Voice Server clusters.
Some environments require redundancy to support critical applications in the event of hardware or software failure. In such environments, a critical application is installed on two or more computers. The computer controlling the application is called the active node, and the other computers are called the standby nodes. This redundant combination of active and standby nodes is called a cluster.
Vocera clustering provides high availability when any of the following events occur:
The computer hardware fails.
The Vocera Voice Server fails.
The Nuance service fails.
The MySQL service fails.
The cluster's active node controls the Vocera system, but a standby node can take over control of the application if the active node fails. The situation where a standby node takes control from the active node is called a failover.
The telephony integration option (Vocera SIP Telephony Gateway, if installed, should run on a server that is separate from the Vocera cluster so telephony support can continue if the Vocera Voice Server fails over. Failover for the telephony server itself is supported as part of the high availability architecture.
The following figure shows the way that the Vocera SIP Telephony Gateway, the Vocera Report Server, and badges connect to a Vocera cluster:
As shown in the above illustration, the nodes in a Vocera cluster do not share a single virtual IP address, as they would with the Microsoft Cluster Service. Instead, the badges, the Vocera SIP Telephony Gateway, and the Vocera Report Server are all associated with 10.42.19.1, the IP address of the active Vocera Voice Server. Similarly, any Administration Console or User Console sessions would also point to the IP address of the active Vocera Voice Server.
Vocera supports a maximum of four cluster nodes (one active node and three standby nodes). Each cluster node maintains its own copy of the Vocera database, the Vocera Report Server log files, and the badge.properties file. The cluster synchronizes these files continually.
If a failover occurs, one of the standby nodes becomes active and takes control of the cluster. At that time, the badges, the Vocera SIP Telephony Gateway, and the Vocera Report Server automatically associate with the IP address of the newly active node, as shown in the following illustration:
As shown in the above illustration, Vocera Voice Server nodes, the Vocera SIP Telephony Gateway, and the Vocera Report Server can reside on different subnets. In a Vocera cluster, the Vocera Voice Server and all its related services are always running on any standby nodes so failover can occur quickly. If the active node fails, a standby node becomes active and takes control of the cluster almost immediately.
You can use the Administration Console or the Vocera Control Panel to determine which node of a cluster is active:
The Vocera Control Panel displays a status message to indicate whether its server is in active or standby mode.
See "Determining the Status of a Server" in the Vocera Installation Guide for complete information.
The Address field of your web browser displays the IP address of the active Vocera Voice Server.
Because each node maintains an independent copy of the database, the Vocera cluster architecture allows disaster survival. The use of multiple nodes will also allow rolling upgrades with minimal down-time in the future.