Set maintenance mode before you perform diagnostic tests, maintenance, or tuning on a node or server. Maintenance mode can prevent the disruption of client requests by routing client traffic that is targeted for a server or node that is in maintenance mode to another server or node.
When a node or server is in running state, the dynamic operations environment considers that node or server to be available for servicing application requests. When problems occur, you must perform diagnostics, maintenance, or tuning on the node or server. Use maintenance mode to stop routing traffic to the node or server while you determine the problem.
When a server is in maintenance mode, the application placement controller cannot control that server. The server does not count toward the minimum or maximum running instances setting for the dynamic cluster. For vertical stacking, the configured maximum minus the number of servers in maintenance mode on the node is used to determine if any servers need to be created on the node. By using this method, the dynamic operations environment does not create or destroy server instances to support the configured maximum number of instances as the dynamic cluster instances move in and out of maintenance mode.
You can use maintenance mode to perform node-level maintenance mode for the ODR nodes just as you can perform node-level maintenance mode for application server nodes. Similarly, you can use server maintenance mode for your ODRs just as you can for application servers.
Two routing policies, the permitMM and permitstickyMM routing policies, are work class match actions that you can use to route HTTP traffic only to servers in maintenance mode. For more information, read about routing and service policies.
HTTP and Session Initiation Protocol (SIP) traffic is no longer routed to the nodes or servers that you have in maintenance mode. Enterprise JavaBeans (EJB) affinity is not broken. Requests with EJB affinity and Java Message Service (JMS) traffic are still routed to the server that is in maintenance mode.