Deployment Manager failures

 

The Deployment Manager is the central control point for all administrative and configurational tasks as well as operational actions. It provides a single image of the whole cell and a mechanism to administer the entire cell.

The Deployment Manager provides several important services to appservers, Node Agents, and application clients. It supports WLM services, administrative services, file transfer service, synchronization service, naming service, security service, PMI, and RAS service.

There are six types of failures in process, network, disk, and machine that may cause the Deployment Manager server to fail: Expected server process failure, for example stopping the server. Unexpected server process failure, for example the server JVM crashes, simulated by kill -9. Server network problem, for example a network cable is disconnected or a router is broken. Unexpected and expected machine problem, for example a machine shutdown, operating system crashes, or power failures. Disk is defective and the configuration file cannot be read. Overloading with heavy hacking or denial of service (DOS) attacks, simulated by continuously running wsadmin to the Node Agent using LoadRunner.

The Deployment Manager is not clustered and therefore is a SPOF in WebSphere V5.1. However, its impact on the application client processing is limited because all configuration data is replicated to every Node Agent in the cell (although the configuration data may be stale or not current).

As soon as the Deployment Manager server becomes available again, all Node Agents in the domain will discover it, and all functions will return to normal.

In the following sections, we discuss the behaviors of Deployment Manager server failures, how WebSphere V5.0 mitigates the impacts of these failures on appservers and application clients, and how to set up the Deployment Manager to tolerate these failures or to minimize the impact of these failures.

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IBM is a trademark of the IBM Corporation in the United States, other countries, or both.