High Availability Considerations

This is one of the infrastructure requirements for a successful STEP setup. The full list is defined in the Infrastructure Requirements topic here.

To achieve system redundancy and an increased amount of system resources for large server solutions, STEP supports the following options for active / active and active / passive clustering.

Active / Active

This option requires both the database and application layer to become fully redundant with at least two (2) active nodes. This can be accomplished via the following ways:

Application

Two or more application servers are configured as an Application Cluster. The cluster is managed by the STEP application (no OS cluster) and will load balance user sessions and processes automatically. In the case of one of the nodes failing, user sessions are automatically transferred and background processes are automatically restarted on the healthy node.

Database

Database clustering is fully managed by Oracle. The active / active clustering option from Oracle is 'Oracle Real Application Cluster' (Oracle RAC).

Active / Passive

Since active / active clustering can be very complex to set up and manage, and has a very high price tag on the Oracle part, an alternative is an active / passive setup, featuring at least two nodes.

Application

An active / passive setup is not directly possible with the application. However, it is possible to setup multiple nodes and configure these for specific purposes. For example, on a three (3) node application setup, the nodes can be dedicated individually for background processes, internal Java client users, and external Web UI users. In case of a breakdown, the system can be reconfigured to use the remaining nodes.

Database

Active / passive clustering on the database is possible with different technologies and setups. The most commonly used is to set up an Oracle 'standby' database server that either shares the database storage with the active node or features its own storage. When using its own storage, the passive node is set up as a standalone database server that must be updated at regular intervals or real-time from the active node. There are multiple ways to update the passive node. The most common way is to use Oracle Dataguard.