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Chapter 11Node Management AgentThis chapter describes how the Node Management Agent (NMA) can be used to monitor and manipulate a cluster. This chapter contains the following sections: Introduction to the Node Management AgentThe NMA is compliant with the Java Management Extensions (JMX) and based on the Java Dynamic Management Kit. The NMA provides access to cluster statistics through the Simple Network Management Protocol (SNMP) or through JMX clients using HTTP. The NMA supports the Internet Engineering Task Force standard RFC 2573. The NMA retrieves statistics about the cluster membership, the reliable transport mechanism, the network file system, and the monitoring of process daemons. The NMA can be used to initiate a switchover, change the maximum number of times that it attempts to restart a daemon, reset the current retry count for a daemon, and listen for certain cluster notifications. The following figure shows a remote client accessing nodes in a cluster. Figure 11-1 Remote Access to the Cluster ![]() Monitoring Statistics With the NMAThe NMA collects two types of statistics: node-level statistics and cluster-level statistics. There is an NMA on each peer node that collects node-level statistics, that is, statistics for that node. Each NMA collects statistics about CGTP, CMM, and the Daemon Monitor. The NMA on each master-eligible node collects node-level statistics about Reliable NFS. The NMA on the master node collects cluster-level statistics, that is, statistics about the cluster. The following table describes the statistics that are collected by the NMA on each peer node and on the master node. Table 11-1 Statistics Collected by the NMA The following statistics can be collected by the NMA:
The NMA running on the master node cascades the statistics from the NMA on each of the peer nodes into its namespace. By cascading, the NMA on the master node can see the statistics on all of the peer nodes. In this way, the NMA on the master node has a view of the entire cluster. The following figure illustrates the cascade of statistics from the peer nodes to the master node. Figure 11-2 Cascading Data From Peer Nodes to the Master Node ![]() A set of NMA APIs can be used to develop applications that monitor and react to the statistics produced by a cluster. For information about developing applications with the NMA APIs, see the Netra High Availability Suite Foundation Services 2.1 6/03 NMA Programming Guide. The statistics that a cluster generates depend on the type, size, and arrangement of the cluster. Each cluster has an individual set of statistics. Knowing the statistics that your cluster generates when it runs correctly can help you to interpret the statistics when the cluster is failing. Use the NMA and its APIs to establish a set of statistics or a benchmark for your cluster when it is working correctly. Manipulating the Cluster With the NMAThe NMA can be configured to initiate a switchover or to change the following Daemon Monitor parameters:
For more information, see the Netra High Availability Suite Foundation Services 2.1 6/03 NMA Programming Guide. | ||
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