Siebel Business Analytics Server Administration Guide > Clustering Analytics Servers >
Chronology of a Cluster Operation
This section provides an overview of the Analytics Cluster Server startup process.
- As each Analytics Server starts, it reads its NQSConfig.INI file. If a server detects a syntax error while reading the file, it logs the error to its NQServer.log file in its Log directory. All syntax errors have to be corrected for startup to continue.
- Each Analytics Server reads its NQClusterConfig.INI file when CLUSTER_PARTICIPANT is set to YES in the NQSConfig.INI file. Cluster Controllers also read this file. If a Analytics Server detects a syntax error while reading the file, it logs the error to its NQServer.log file. If a Cluster Controller detects an error while reading the file, it logs the error to its NQCluster.log. If a machine is hosting both a Analytics Server and a Cluster Controller, messages will be written to both logs. All syntax errors have to be corrected for startup to continue.
- The Analytics Server verifies the presence of an active, operational Cluster Controller. If the machine hosting the primary Cluster Controller is not available, the Analytics Server will contact the machine designated as the secondary if a secondary has been defined. If no Cluster Controller can be located, cluster startup will fail.
- The primary and secondary Cluster Controllers begin to exchange heartbeat messages. (This step is omitted when no secondary Cluster Controller is defined.)
- The Analytics Server verifies whether the repository publishing directory is available. If the repository publishing directory is not available, the action each server takes depends on the setting for the REQUIRE_PUBLISHING_DIRECTORY parameter in its NQSConfig.INI file. When set to YES, if the publishing directory is not available at startup or if an error is encountered while the server is reading any of the files in the directory, an error message is logged in the NQServer.log file and the server shuts down. When set to NO, the server joins the cluster and a warning message is logged in the NQServer.log file, but any online repository updates are not reflected in the server's Repository directory.
- The primary and secondary Cluster Controllers begins to exchange heartbeat messages with each server that is to participate in the cluster. The connection status is logged in the NQServer.log files of all servers in the SERVERS list. Messages are also logged in the Cluster Controller's NQCluster.log file. Any servers with connection problems are not be allowed to join the cluster. If the server defined as the MASTER_SERVER for online repository is not available, no repository editing in online mode will be possible.
- As each Analytics Server in the cluster is started, it examines the repository publishing directory for any updated repositories. This is done by comparing the date and timestamps. (The administrator is responsible for making sure that the time of day clocks are synchronized across all Analytics Servers and Cluster Controllers.) If a server detects a newer version of an existing repository, it copies the repository to its own Repository directory. A server will not detect the presence of any new repositories; a new repository must be manually propagated to all clustered servers when it is initially created. After that, online changes are detected at subsequent startups of each server.
- When the Cluster Controller assigns a session to a particular Analytics Server, the server communicates with the back-end database using the connection defined in the Connection Pool dialog box for the database. Clustered servers do not share a common connection pool.
- If an Analytics Server determines it can satisfy all or a portion of a query from its cache file, it will do so. Clustered servers do not share a common cache.