Fault-Tolerance with FTL Stores
As a storage mechanism, a cluster of coordinating FTL servers provides data persistence and replication features that support Shared State fault-tolerance in EMS. The FTL server cluster must be formed of 3 constituent FTL servers in order to support EMS fault-tolerance with FTL stores. A single FTL server can only be configured to run a standalone EMS server with FTL stores.
Each FTL server in the cluster has its own EMS server running under it. One of the 3 FTL servers in the cluster is set to standby_only
mode, meaning that its corresponding EMS server will always remain in fault-tolerant standby mode and can never transition to active state. This server’s only purpose is to perform data replication and provide redundancy. The EMS servers belonging to the two FTL servers that are not standby_only
comprise the actual fault-tolerant EMS server pair. One of these is chosen by the cluster to enter the active state and the other becomes its fault-tolerant peer in standby state.
A client making a fault-tolerant connection to these EMS servers would specify only the URLs of the fault-tolerant EMS server pair. The URL of the EMS server running under the standby_only
FTL server should not be used since that EMS server will never activate.
The fault-tolerant EMS server pair makes use of the connections between the FTL servers in the cluster for fault-tolerance related communication. This means that the specifics of fault-tolerance are handled by the FTL server cluster rather than the EMS servers themselves. The majority of EMS server parameters and options relating to configuration of fault-tolerance are not applicable when using FTL stores.
When using FTL stores, the EMS server configuration is stored in the FTL server cluster. This allows the configuration to be accessible to EMS servers running in separate machines or containers. Static configuration elements including JAAS modules, JAAS module configuration files, JACI modules and digital certificates are not stored in the cluster and must still be maintained manually.
FTL stores have been designed such that an EMS user should be able to deploy them with minimal knowledge of TIBCO FTL. The following sections cover all information required for configuring and deploying EMS with FTL stores. If you would like to learn more about FTL servers or FTL in general, refer to the TIBCO FTL Administration product guide.