You can create a dynamic cluster of on demand routers (ODRs),
which means that the application placement controller selects the
best node on which to start the minimum number of ODRs. If an ODR
stops for any reason, the application placement controller will then
start a new instance.
Before you begin
- The size of an ODR dynamic cluster will not currently increase
beyond the minimum number of instances.
- Before running the manageODR.py script, ensure that you have the
WAS_HOME environment variable configured to point to the directory
of your WebSphere® installation.
- When an ODR is a member of a cluster, routing rules and other
configuration settings that are set at the ODR level are ignored.
Configuration settings at the cluster level take precedence over any
configuration settings at the server level.
- For Session Initiation Protocol (SIP), an ODR cluster defines
the other ODRs to which an ODR can route. An ODR might route a UDP
message to another ODR to guarantee that server affinity is maintained
in the case that the UDP message is a retransmission.
Avoid trouble: The SIP ODR is stabilized,
and is currently not recommended. Use the SIP proxy server instead.
About this task
You can configure a dynamic cluster isolation policy to
prevent ODRs from running on the same node with application servers.
You can use the administrative console, or you can run the manageODR.py
script to create ODR dynamic clusters. You can also set a cell-level
custom property to enable elasticity mode for ODR dynamic clusters.
Procedure
- Create ODR dynamic clusters in the administrative console
to create ODR dynamic clusters.
- Click .
- Select On demand router as the
dynamic cluster server type.
- Select the membership method, which defines how servers
join the dynamic cluster as cluster instances.
Select Automatically
define cluster members with rules to create a membership
policy that defines the nodes on which cluster instances can be placed.
Select Manually define cluster members to add
existing servers to the dynamic cluster. The servers that you select
must be homogenous: that is, they must be of the same server type,
middleware server version, and have the same applications installed.
- Define the dynamic cluster members.
- Select a dynamic cluster template.
Deprecated feature: The defaultXD
and
defaultXDZOS
server templates that are used when creating a dynamic cluster are
deprecated. Use the default
or defaultZOS
server template
instead.
- Specify dynamic cluster-specific properties.
- Confirm the creation of the ODR dynamic cluster.
Click to save the changes to the master configuration.
- Select the mode of operation.
Select . Choose the operational mode, and click Set
mode.
- Run the manageODR.py script to create ODR dynamic clusters.
The manageODR.py script is in the install_root/bin directory.
In the following example, an ODR dynamic cluster named myOdrCluster is created on all nodes in
the node group named
myOdrNodeGroup.
./wsadmin.sh -f manageODR.py createDynamicCluster myOdrCluster myOdrNodeGroup
- Set the APC.predictor custom property to enable elasticity
mode for ODR dynamic clusters.
By setting the custom property,
the application placement controller starts and stops servers based
on CPU usage alone. Furthermore, the controller no longer retrieves
data from the autonomic request flow manager (ARFM) regarding what
servers to start and stop.
- Click .
- Specify the name of the custom property as APC.predictor.
- Specify the value of the custom property as CPU.
- Click OK, and save and synchronize
your changes.
What to do next
- After you create your ODR dynamic clusters, you can manage them
from the Dynamic clusters panel in the administrative console. Click .
- Monitor performance with reports and operations tabs. Click . Select the Reports tab or
the Operations tab.