(ZOS) Precedence for modify command parameters, request-level RAS attributes, and server-wide properties

Three ways exist to define Reliability Availability and Serviceability (RAS) attribute values: server-wide properties, request-level RAS attributes, or modify command parameters. Modify command parameters have precedence over associated RAS attributes and server-wide properties, while the RAS attributes have precedence over the associated server-wide properties.

The following list describes the order of precedence:

• The modify command takes precedence over the associated RAS attributes and server-wide properties.

  After you invoke a modify command, the command applies to all requests, regardless of the server-wide properties or the classification attributes that we have defined.

• The request-level RAS attributes defined in the workload classification file take precedence over the associated server-wide property settings.

  • If we specify request-level RAS attribute values on the HTTP classification element, the request-level RAS attribute values override the server-wide property settings for HTTP requests.

  • If we specify request-level RAS attribute values on the IIOP classification element, the request-level RAS attribute values override the server-wide property settings for IIOP requests.

  • If we specify request-level RAS attribute values on the optimized local adapter classification element, the request-level RAS attribute values override the server-wide property settings for optimized local adapter requests.
  • If we specify request-level RAS attribute values on the classification element for the message-driven bean (MDB) whose listener exists in the control region, the request-level RAS attribute values override the server-wide property settings for those MDB requests.
  • If we specify request-level RAS attribute values with the activation specification in the control adjunct region, the request-level RAS attribute values override the server-wide property settings for those DB requests.

The server-wide property settings continue to apply to any protocols that the request-level RAS attribute does not apply.

A RESET value is available on all modify commands that have corresponding server-wide properties that also have associated RAS attributes. The RESET value deactivates the modify command override. After a reset is invoked, the server returns to the server-wide properties and RAS attributes that were in effect before the modify override became activated.

Remember: How a RAS attribute takes effect depends on how we define the RAS attribute.

• If we define the RAS attribute as a server-wide property, we must restart the application server.

• If we define the RAS attribute as a request-level RAS attribute, we have two options. We can restart the application server or reload the workload classification document without having to restart the application server.

• If we define the RAS attribute with the modify command, the modify command takes effect dynamically without requiring a restart of the server.

Several of the RAS attributes added to the workload classification file are associated with server-wide environment properties which are associated with modify commands. For example, the SMF_request_activity_enabled request-level RAS attribute is associated with the server_SMF_request_activity_enabled server-wide property, which in turn is associated with the SMF,REQUEST modify command.

The SMF_request_activity_enabled request-level RAS attribute specifies whether the application server collects System Management Facilities (SMF) 120 subtype 9 records for requests. The requests can be HTTP requests, IIOP requests, optimized local adapter requests, or MDB requests that have the listener in the control region. The request-level RAS attribute is coded on the HTTP classification element for HTTP requests, on the IIOP classification element for IIOP requests, on the optimized local adapter classification element for optimized local adapter requests, and on the MDB classification element for MDB requests.

The server_SMF_request_activity_enabled server-wide property specifies whether the application server collects SMF 120 subtype 9 records for all requests that the application server processes.

The SMF_request_activity_enabled request-level RAS attribute overrides the server_SMF_request_activity_enabled server-wide property for any HTTP requests, IIOP requests, optimized local adapter requests, or MDB requests that have the listener in the control region. Like the server-wide property, the SMF,REQUEST modify command specifies whether the application server collects SMF 120 subtype 9 records for all requests that the application server processes. However, the modify command dynamically overrides the settings for the request-level RAS attribute and the server-wide property without requiring a restart of the server.

The example shows the following capabilities:

• The server-wide property of server_SMF_request_activity_enabled is in effect.

• The SMF_request_activity_enabled request-level RAS attribute can override the server_SMF_request_activity_enabled server-wide property.

• The SMF,REQUEST modify command can override both the server-wide property and the request-level RAS attribute.

• The reset option on the SMF request modify command can deactivate the modify command override.

Here are the particulars for each of the capabilities:

• You set the server-wide property of server_SMF_request_activity_enabled to 1 on the administrative console. The RAS attributes and the modify command do not override the property. All requests that the server processes collect SMF 120 subtype 9 records.

• You next create a workload classification document, which defines a single http_classification_info element:

  <http_classification_info	
      uri="/PlantsByWebSphere/*"
      SMF_request_activity_enabled="0" 
    />
  

  The HTTP classification element specifies that the SMF_request_activity_enabled request-level RAS attribute is set to 0. This request-level RAS attribute overrides the server_SMF_request_activity_enabled server-wide property that is set to 1. None of the HTTP requests with a URI that begins with /PlantsByWebSphere/ collect SMF 120 subtype 9 records. All HTTP requests with URI that do not begin with /PlantsByWebSphere/, and all requests from non-HTTP protocols, observe the server-wide property setting. Those requests continue to collect SMF 120 subtype 9 records.

• You now issue the following modify command:

  MODIFY BBOS001,SMF,REQUEST,ON
  

  The modify command specifies that SMF 120 subtype 9 record collection is on. The modify command overrides the SMF_request_activity_enabled request-level RAS attribute which is off since it is set to 0. Therefore, all HTTP requests with URI that begin with /PlantsByWebSphere/ collect SMF 120 subtype 9 records. The modify command also overrides the server_SMF_request_activity_enabled server-wide property which is on since it is set to 1. However, the server_SMF_request_activity_enabled server-wide property and the modify command override are both on. Therefore, all requests that observed the server-wide property before we issued the modify command experience no change in behavior. Those requests continue to collect SMF 120 subtype 9 records.

  You next issue the following modify command:

   MODIFY BBOS001,SMF,REQUEST,OFF
  

  The OFF value means that SMF 120 subtype 9 record collection is turned off. The modify command overrides the SMF_request_activity_enabled request-level RAS attribute. However, the request-level RAS attribute is also off since it is set to 0. So, no change in behavior occurs. Both the modify command and the request-level RAS attribute turned off the collection of SMF 120 subtype 9 record collection for HTTP requests with URI that begin with /PlantsByWebSphere/. The modify command also overrides the server_SMF_request_activity_enabled server-wide property which is on since it is set to 1. Therefore, all other HTTP requests and all non-HTTP requests, that had observed the server_SMF_request_activity_enabled server-wide property that is set to 1 no longer collect SMF 120 subtype 9 records.

• You next issue the following modify command:

  MODIFY BBOS001,SMF,REQUEST,RESET
  

  The RESET value causes the modify command override to be deactivated. This means that all HTTP requests with a URI that begins with /PlantsByWebSphere/ go back to observing the SMF_request_activity_enabled request-level RAS attribute set to 0. None of the HTTP requests with a URI that begins with /PlantsByWebSphere/ collect SMF 120 subtype 9 records. All other HTTP requests, and all non-HTTP requests, go back to observing the server_SMF_request_activity_enabled server-wide property that is set to 1 by collecting SMF 120 subtype 9 records.

Enable request-level Reliability Availability and Serviceability (RAS) granularity

Modify command

Workload classification file