Occasionally, you might encounter application placement behavior
that is not expected. This topic describes some common things to look for
when application placement is not working, or not working the way that you
expect.
Application placement changes are not occurring when
you expect
Depending on your administrative role, you are allowed specific
privileges when configuring the autonomic managers. The following list shows
the administrative roles and privileges for configuring the autonomic managers:
- Monitor
- Can view the information.
- Operator
- Can view the information on the configuration tab.
- Can change the settings on the runtime tab.
- Configurator
- Can change the configuration but not the runtime settings.
- Administrator
- Has all privileges.
If you find your application placement changes are occurring
in an unexpected fashion, use the following course of action:
- Verify that the placement controller is enabled. In the administrative
console, click Operational policies > Autonomic Managers > Application
placement controller. Verify that the placement controller is enabled.
- Verify that the subject cluster or clusters are dynamic clusters. The
application placement controller acts upon dynamic clusters only. In the administrative
console, click Servers > Dynamic clusters. Check that the Operational
Mode field for each of the subject clusters is Automatic. If not,
select the dynamic clusters and click Automatic. After you select automatic
for your dynamic clusters, click Set Mode.
- Verify that the configured minimum time between placement change parameters
is not set too high. In the administrative console, click Operational policies
> Autonomic Managers > Application placement controller. Set the value
in the Minimum time between placement changes field to a suitable value.
Acceptable values range from 1 minute to 24 hours.
- Verify that the configured application placement controller cycle is not
too long. To modify that setting from the administrative console, click Operational
policies > Autonomic controllers > Application placement controller > Custom
properties. Add a custom property, by clicking New. In the Name
field, enter minControlCycleLength and in the Value field, provide
a suitable time value in minutes, such as 1.
If the problem still persists after making these suggested changes
and restarting the cell, verify the following problems.
Dynamic cluster members are not inheriting properties from
the template
You must save dynamic clusters to the master repository
before making changes to the server template. If you have dynamic cluster
members that do not inherit the properties from the template, the server template
probably incurred changes in an unsaved workspace. To fix this issue, delete
the dynamic cluster, then recreate it.
Save your changes to the master
repository. You can ensure that your changes are saved to the master repository
after clicking Finish, by clicking Save in the message window
in the top frame. Click Save again in the Save to Master Configuration window.
Click Synchronize changes with nodes.
Not enough active servers in a dynamic cluster
If
you encounter problems where not enough servers are running in the dynamic
cluster, try the following actions:
- When the nodes in the node group are not highly utilized, verify the service
policy is met. At times the policy might not be defined clearly and although
the system is able to meet them, although not to your expectations. To check
or change a service policy in the administrative console click Operational
policies > Service policies > Select an existing policy. Check
the goal type, goal value, and importance of the policy, and make any necessary
changes.
- When the nodes in the node group are highly utilized, compare the service
policy goals of this cluster to service policy goals of other active clusters.
If the traffic that belongs to this cluster has lower importance or looser
target service goals relative to the other clusters, it is more likely that
the system instantiates fewer servers for this cluster. To check or change
a service policy in the administrative console, click Operational policies
> Service policies > Select an existing policy.
- When the node group seems to have some extra capacity, but your service
policies are not met, check the configuration settings on the dynamic cluster.
There might be too few instances of the dynamic cluster created as a result
of the maxInstances policy setting.