Creating a health policy: Define health policy general properties
Use this page to create health policies, which are used to perform
a variety of health-based assessments on clusters, dynamic clusters, and application
server instances running on nodes.
To view this administrative console page, click Operational policies
> Health policies > New.
Privileges for health policies differ, depending on the user’s administrative
role. Roles include monitor, operator, configurator, and administrator.
If you are a user with either a monitor or an operator role, you can only
view health policy information. If you are a user with either a configurator
or an administrator role, you have all configuration privileges for health
policies.
When you complete all of the required fields, click Next to proceed.
- Name
Specifies the name of a health policy. The health policy name is
required and must be unique among all the health policies in the cell.
The name cannot begin with a period (.) or
a space. A space does not generate an error, but leading and trailing spaces
are automatically deleted. Use meaningful and consistent health policy names.
For example, age-based health policies can be indicated by naming the policies AGE_20DAYS, AGE_15DAYS, and so on.
- Description
Specifies an additional description of the health policy. The description
is optional. You can edit the description when you are creating or editing
a health policy. Consider using the optional description when you are using
many health policies or when multiple administrators manage the same set of
health policies.
- Predefined health condition
The health condition defines the specific policy that is implemented.
Predefined health conditions are those that ship with WebSphere Extended Deployment.
Some policies are prevention-based and some are detection-based.
Prevention-based policies are used to avoid conditions that might lead to
problems, while the detection-based policies are used to identify existing
conditions and to achieve resolution. These policies can be used to perform
health-based assessments on clusters, dynamic clusters, and application server
instances running on nodes. In the case of dynamic clusters, regardless of
the health policy that you are using, the minimum number of dynamic cluster
instances remains running.
- The age-based condition policy restarts the associated members
when their age reaches a certain user-defined value. This restart cleans out
all cached and memory acquired data. If you select age-based condition policy,
you must define the age criteria. The age-based condition
is supported for all server types.
- The excessive request timeout condition policy tracks the memory
that is used for request timeouts. When the percentage of timeouts exceeds
the breach of condition, the members are restarted. If you select the excessive
request timeout condition, you must set the memory used percentage threshold. The excessive request timeout condition is supported for
all server types.
Restriction: The excessive request timeout
condition does not apply to Java Message Service (JMS) and Internet Inter-ORB
Protocol (IIOP) traffic.
- The excessive response time condition policy tracks the requests
and the amount of time they take to complete. Use this policy to clean up
servers that have an average number of requests that take longer than a specified
time. If an average number of requests takes longer than a certain amount
of time, the members are restarted. When you select the excessive response
time policy, you must define the response time threshold. The
excessive response time condition is supported for all server types.
- The memory condition: excessive memory usage policy tracks the
memory usage for a member. When the memory usage exceeds a percentage of the
heap size for a specified time, actions are taken to correct this situation.
If you define the health policy against a standalone server, static cluster,
or dynamic cluster in manual mode, then the member stops and restarts. If
you define the health policy against a dynamic cluster that is in automatic
or supervised mode, then the member that is flagged by the condition stops.
The placement controller dynamically decides which, if any, servers to start
based on its evaluation of the environment. These actions occur automatically
if you are in automatic mode. If you are in supervised mode, you can approve
the runtime tasks are generated to correct the situation. If you select the
excessive memory usage policy, you must define the memory used and the time-over-memory
threshold. The excessive memory usage condition is
supported only on application servers on nodes that run WebSphere Application
Server or WebSphere Application Server Community Edition.
You cannot define the excessive memory usage condition for other middleware
server types.
- The memory condition: memory leak policy tracks consistent downward
trends in free memory that is available to a server in the Java heap. The
detection level setting determines when these trends are detected. If you
select the memory condition: memory leak policy, you must define a detection
level. The slower detection level setting requires the most historical data.
The normal and faster detection level settings require the same amount of
historical data, but the faster setting allows analysis before the Java heap
has expanded to its maximum configured size. This provides earlier detection
capability, but is also more prone to false positives. This condition supports
heap dumps in addition to server restarts as reactions. The
memory leak condition is not supported for other middleware server types.
- The storm drain condition policy tracks stuck requests. The server
that is associated with this policy restarts when the specified detection
level is reached. Storm drain detection relies on change point detection on
a given time series data. The metrics that are used for detecting storm drain
are the response times and deployment workload manager weights that are observed
for the server. The storm drain condition applies only to dynamic clusters
and cells. If you select the storm drain condition policy, you must select
the detection level.
To detect change points, the health controller calculates
a left mean and a right mean for a given point. For a point, the left mean
consists of the mean value of N samples that arrive prior to this sample,
and the right mean is the mean value of N samples, including the current
point, that arrive later. The difference of the left and the right mean values
is stored and compared with other differences in a set of values to N to
determine if this difference is a local maxima. If this difference is the
maximum difference, then the point to which this difference corresponds, is
declared as a change point. The two metrics that are used for detecting
storm drain are the response times and dynamic workload manager weights that
are observed for the server.
The storm drain condition
is supported for all server types.Restriction: The storm
drain condition does not apply to JMS and IIOP traffic.
- The workload condition policy restarts the members when a certain
user-defined number of requests are serviced. This policy cleans out the memory
and caches. If you select the workload policy, you must define the total request
criteria. The workload condition is supported for all
server types.
- Custom health condition
You can define health conditions if the existing health conditions
do not fit your needs. Custom health conditions can be tested against metrics
in your environment.
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