TIBCO Enterprise Message Service™ Instances

On a given appliance, a TIBCO Enterprise Message Service instance is an EMS server running on the appliance.

The TIBCO Enterprise Message Service™ Appliance identifies a running EMS server as either instance 0 or instance 1. The instance number is set when the appliance software is initialized. This process is described in Initializing the Software.

The availability of EMS server instances depends on the appliance configuration.

  • Single Appliance Configuration

    In a single appliance deployment, only one instance is available. This instance is always instance 0, and runs in standalone mode.

  • Fault Tolerant Configuration

    When two appliances (Peer-A and Peer-B) are connected as a fault tolerant pair, there are two TIBCO Enterprise Message Service™ instances, and each appliance is running two EMS servers, instance-0 and instance-1. For a given instance, the servers of that instance on each peer coordinate in order to synchronize and replicate data, with one running as active and the other as warm-standby. This state replication mechanism synchronizes and replicates configuration and store files between two appliances in a fault tolerant pair.

    During normal load-balanced Fault-Tolerant operation, each instance has an Active EMS server running on one peer and a Standby EMS server running on the other peer so that each appliance is running one Active and one Standby server. By default, an EMS server is Active on its primary appliance (Peer-A for instance-0 and Peer-B for instance-1) and Standby on its secondary appliance (Peer-B for instance-0 and Peer-A for instance-1).

  • Disaster Recovery Configuration

    When four appliances are configured for disaster recovery, each pair in the quad is set up similar to a fault tolerant configuration. That is, at each site there is an appliance with an EMS server instance 0 designated as primary, and a second appliance where the primary EMS server instance is identified as instance 1.

    Note that during normal DR operations the EMS servers at the backup site are disabled.