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.
Before you begin
You can set maintenance mode on a server or a node that is
represented in the administrative console.
To view the nodes that
are configured, click . To view all
of the servers that are configured, click .
You can use
maintenance mode when you route requests with on demand routers (ODR)
or proxy servers. If you are using a Web server to route requests,
then maintenance mode is not recognized.
About this task
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.
Two routing policies, the permitMM and
permitstickyMM routing policies, are work class match actions that
you can use to only route HTTP traffic to servers in maintenance mode.
See Routing and service policies for more information.
Procedure
- Place nodes into or out of maintenance mode.
- Select the nodes. In the administrative console,
click . Select the
nodes for which you want to change the maintenance mode.
- Select the maintenance mode.
- Maintenance mode: The on demand router (ODR) will continue
to send requests with affinity to an application server in this mode,
but will typically 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.
- Click Set mode.
- Place servers into or out of maintenance mode. In
the administrative console, click . Select the servers
for which you want to change the maintenance mode.
- Select the servers.
- Select the maintenance mode.
- Maintenance mode: The ODR will continue to
send requests with affinity to an application server in this mode,
but will typically 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 will typically
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 mode - 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.
- Click Set mode.
Results
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.
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.