Set maintenance mode

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.

• We can set maintenance mode on a server or a node that is represented in the administrative console.

• To view the nodes configured, click System administration > Middleware nodes. To view all of the servers configured, click Servers > All servers.

• We can use maintenance mode when you route requests with on demand routers (ODR) or proxy servers. For a web server to route requests, maintenance mode is not recognized.

• ODR maintenance mode is supported when the ODR is fronted by a web server plug-in. The plugin-cfg.xml file generator generates the plug-in appropriately to enforce the various modes of node and server maintenance mode. We can use node and server maintenance mode to apply service to the ODR tier in the same way that you use maintenance mode to apply service to the application server tier.

• Set a server into maintenance mode is a persistent change. A server remains in maintenance mode even if the server is restarted, until the mode is explicitly changed. The maintenance mode of a server is stored persistently as a server custom property. The name of the custom property is server.maintenancemode.

  The server.maintenancemode property values can be:

  • false: This value disables the maintenance mode.

  • break: Stops any traffic from being routed to the server.

  • affinity: This value routes only traffic with affinity to the server.

  • stop: Stops the server, and persistently sets it in break mode.

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, 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.

We can use maintenance mode to perform node-level maintenance mode for the ODR nodes just as we can perform node-level maintenance mode for application server nodes. Similarly, we can use server maintenance mode for the ODRs just as we can for application servers.

Two routing policies, the permitMM and permitstickyMM routing policies, are work class match actions that we can use to route HTTP traffic only to servers in maintenance mode. For more information, read about routing and service policies.

1. Place nodes into or out of maintenance mode.

   1. Select the nodes. In the administrative console, click System administration > Middleware nodes. Select the nodes for which to change the maintenance mode.

   2. Select the maintenance mode.

      Maintenance mode

      The on demand router (ODR) continues to send requests with affinity to an application server in this mode, but typically does not send requests without affinity (unless the request matches a rule which explicitly permits it to be routed to an application server in maintenance mode).

      Maintenance immediate stop

      This mode is the same as the break affinity mode, except that the application server is also immediately stopped. When the application server is restarted, it is still in break affinity mode.

      Normal

      The ODR sends requests with and without affinity to an application server in this mode.

   3. Click Set mode.

2. Place servers into or out of maintenance mode. In the administrative console, click Servers > All servers. Select the servers for which to change the maintenance mode.

   1. Select the servers.

   2. Select the maintenance mode.

      Maintenance mode

      The ODR continues to send requests with affinity to an application server in this mode, but typically does not send requests without affinity (unless the request matches a rule which explicitly permits it to be routed to an application server in maintenance mode).

      Maintenance mode - break affinity

      The ODR typically does not send any requests to an application server in this mode (unless the request matches a rule which explicitly permits it to be routed to an application server in maintenance mode).

      Maintenance immediate stop

      This mode is the same as the break affinity mode, except that the application server is also immediately stopped. When the application server is restarted, it is still in break affinity mode.

      Normal

      The ODR sends requests with and without affinity to an application server in this mode.

   3. Click Set mode.

   After a server is placed into maintenance mode, the changes are synchronized in all nodes. If the cell level custom property maintenanceModeSyncContainingNodeOnly is set to true, the changes are synchronized with the node on which the server resides. This custom property takes effect dynamically. No restart is required.

Results

HTTP and Session Initiation Protocol(SIP) traffic is no longer routed to the nodes or servers that we have in maintenance mode. 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.

What to do next

The health controller also uses server maintenance mode as an action that is taken when the health policy is breached. For example, if you are using an excessive response time condition, and the response time exceeds the specified maximum for a server, then the server can move to maintenance mode.

Subtopics

• (dist)(zos) Intelligent Management: maintenance mode administrative tasks
  We can use the server maintenance mode commands to view or edit the maintenance mode of the servers without using the administrative console. To set maintenance mode on a node, we can use the NodeGroupManager MBean .

Related tasks

Create health policies

Create ODRs

Route to servers that are in maintenance mode

Intelligent Management: maintenance mode administrative tasks

Intelligent Management: routing and service policies