Fault Tolerance in EMS

You can arrange TIBCO Enterprise Message Service servers for fault-tolerant operation by configuring a pair of servers—one primary and one backup. The primary server accepts client connections, and interacts with clients to deliver messages. If the primary server fails, the backup server resumes operation in its place. (EMS does not support more than two servers in a fault-tolerant configuration.)

Shared State: A pair of fault-tolerant servers must have access to shared state, which consists of information about client connections and persistent messages. This information enables the backup server to properly assume responsibility for those connections and messages.

Server state includes 3 categories of information:

• Persistent messages


• Client connections of the primary server


• Metadata about message delivery (stored in the meta.db file)

Persistent messages are stored in 2 files: async-msgs.db file, which contains all the messages stored under normal mode, and sync-msgs.db file that contains all messages that are for failsafe destinations

Locking: To prevent the backup server from assuming the role of the primary server, the primary server locks the shared state during normal operation. If the primary server fails, the lock is released, and the backup server can obtain the lock.

Click to read about Configuring Fault Tolerance.