Core group custom properties

Use these custom properties for advanced configurations for core groups.

Note: This topic references one or more of the application server log files. As a recommended alternative, you can configure the server to use the High Performance Extensible Logging (HPEL) log and trace infrastructure instead of using SystemOut.log , SystemErr.log, trace.log, and activity.log files on distributed and IBM® i systems. You can also use HPEL in conjunction with your native z/OS® logging facilities. If you are using HPEL, you can access all of your log and trace information using the LogViewer command-line tool from your server profile bin directory. See the information about using HPEL to troubleshoot applications for more information on using HPEL.

To configure a custom property, on the indicated Custom properties page, complete one of the following actions:

  • If the custom property is in the list of defined custom properties, click on that property and then enter an appropriate value in the Value field.
  • If the custom property is not in the list of defined custom properties, click New and then enter the name of the custom property in the Name field and an appropriate value in the Value field.
Best practice: When you set the core group custom properties, make sure that the core group or the cell is in a stable state. You do not want to set these custom properties when you are simultaneously starting or stopping servers. Also, ensure that the high availability manager is in a known, good state. With these best practices in mind, consider the following best practices for some specific core group custom properties:
  • When you set the IBM_CS_WIRE_FORMAT_VERSION custom property to 6.1.0, the value is automatically detected and applied to all nodes. You do not need to stop or start servers. For information on the custom property, see the IBM_CS_WIRE_FORMAT_VERSION custom property description.
  • Although you can set the IBM_CS_HAM_PROTOCOL_VERSION custom property value in a topology in which only a single core group exists, it does not provide any benefit. However, if you need to later partition a cell into multiple core groups and bridge them together, it is better to have the core groups running the most current possible protocol version before you start the bridges. If your topology contains multiple core groups that are bridged together, set this value to the most current possible version. For the applicable values and information on how to set this custom property, see the IBM_CS_HAM_PROTOCOL_VERSION custom property description.
You can use the custom properties page to define the following core group custom properties:

IBM_CS_DATASTACK_MEG

Use this custom property to eliminate a condition that is reported by a message that is displayed repeatedly in your SystemOut.log file.

Tip: This topic references one or more of the application server log files. As a recommended alternative, you can configure the server to use the High Performance Extensible Logging (HPEL) log and trace infrastructure instead of using SystemOut.log , SystemErr.log, trace.log, and activity.log files on distributed and IBM i systems. You can also use HPEL in conjunction with your native z/OS logging facilities. If you are using HPEL, you can access all of your log and trace information using the LogViewer command-line tool from your server profile bin directory. See the information about using HPEL to troubleshoot applications for more information on using HPEL.
Deprecated feature: This custom property is deprecated. Do not use this custom property unless you are running in a mixed cell environment that includes at least one core groups that contains a mixture of Version 7.0 and Version 6.x processes.
Mixed-version environment: If you are running in a mixed cell environment, and you have core groups that contain a mixture of Version 7.0 and Version 6.x processes, you must continue to use the IBM_CS_DATASTACK_MEG core group custom property to change how frequently the Discovery Protocol attempts to open a new network.

You might see a message, similar to the following message, repeated multiple times in the SystemOut.log file:

[9/24/04 13:28:19:497 CDT] 00000013 VSync         W   
DCSV2005W: DCS Stack DefaultAccessPointGroup.P at Member 172.16.1.86:9353: 
The amount of memory available for synchronization is low. The configured memory 
size is 418816 bytes. Currently used memory size is 420307 bytes.

If the member IP address is in the format of a dotted decimal IP address and port, you can eliminate these messages by increasing the amount of memory that is allocated to the core stack that is used for core group communication. Increase the value of this property until you no longer see the message in your SystemOut.log file. Because the memory is dynamically allocated, setting a larger stack size than you need does not cause memory problems.

Note: You can also set this custom property:
  • On the core group bridge interface that contains the particular core group member that is in the messages.
  • On the access point group or the core group access point for the particular core group member that is in the messages.

See Core group bridge custom properties for more information about how to set the property at those levels.

Table 1. Units and default. The following table describes the units and default for the setting.
Units Megabytes
Default 5

To set a value for this custom property, in the administrative console, click Servers > Core Groups > Core group settings > core_group_name. Then, under Additional Properties, click Custom properties.

IBM_CS_FD_CONSECUTIVE_MISSED

This custom property is used to specify the consecutive number of heartbeats that must be missed before the core group member is considered failed.

Deprecated feature: This custom property is deprecated. Do not use this custom property unless you are running in a mixed cell environment that includes at least one core groups that contains a mixture of Version 7.0 and Version 6.x processes.

However, you can also use the Discovery and failure detection page in the administrative console to change the settings for the Discovery and Failure Detection protocols. Unless you are running in a mixed cell environment, using the administrative console is the preferred technique for changing the settings for the Discovery and Failure Detection protocols because the IBM_CS_FD_CONSECUTIVE_MISSED property is deprecated.

Mixed-version environment: If you are running in a mixed cell environment, and you have core groups that contain a mixture of Version 7.0 and Version 6.x processes, you must continue to use the IBM_CS_FD_CONSECUTIVE_MISSED core group custom property to change how many consecutive heartbeats a core group member must miss before that core group member is considered failed.
Table 2. Units and default. The following table describes the units and default for the setting.
Units Seconds
Default 6

To set a value for this custom property, in the administrative console, click Servers > Core Groups > Core group settings > core_group_name. Then, under Additional Properties, click Custom properties.

IBM_CS_FD_PERIOD_SECS

This custom property is used to change how frequently the Failure Detection Protocol checks the core group network connections that the discovery protocol establishes. The Failure Detection Protocol notifies the Discovery Protocol if a connection failure occurs.

Deprecated feature: This custom property is deprecated. Do not use this custom property unless you are running in a mixed cell environment that includes at least one core groups that contains a mixture of Version 7.0 and Version 6.x processes.

However, you can also use the Discovery and failure detection page in the administrative console to change how frequently the high availability manager Discovery Protocol checks for new core group members. Unless you are running in a mixed cell environment, using the administrative console is the preferred technique for updating this setting because the IBM_CS_FD_PERIOD_SECS property is deprecated.

Mixed-version environment: If you are running in a mixed cell environment, and you have core groups that contain a mixture of Version 7.0 and Version 6.x processes, you must continue to use the IBM_CS_FD_PERIOD_SECS core group custom property to change how frequently the Failure Detection Protocol checks the core group network connections that the discovery protocol establishes.
Table 3. Units and default. The following table describes the units and default for the setting.
Units Seconds
Default 6

To set a value for this custom property, in the administrative console, click Servers > Core Groups > Core group settings > core_group_name. Then, under Additional Properties, click Custom properties.

IBM_CS_HAM_PROTOCOL_VERSION

Use this custom property to configure all of the members of the selected core group to run with a different version of the higher level core group protocol, which is also referred to as the high availability manager protocol. You can change the value of this property while the core group members continue to run. After you save and synchronize the changed value to all of the nodes containing core group processes, the high availability manager automatically detects the configuration change and starts using the new core group protocol version to communicate with the core group members.

Table 4. Version ID and description. The following table lists the supported core group protocol version IDs.
Version ID Required Minimum Product Level Description
6.0.2.31 6.0.2.31 for Version 6.0, 6.1.0.19 for Version 6.1, 7.0.0.1 for Version 7.0 This protocol version is the original or base version of the HAM protocol. This version was included in the 6.0.2.31, 6.1.0.19, and 7.0.0.1 service packs to facilitate core group bridge scalability. This version is recommended for topologies that contain multiple core groups and core group bridges as part of their configuration.
Set this custom property to the value in the Version ID column of the previous table. To set this custom property, complete the following process:
  1. Stop the core group bridges.
  2. Set the custom property on all core groups.
  3. Restart the high availability coordinators in all core groups.
  4. Start the core group bridges.

IBM_CS_IP_REFRESH_MINUTES

Use this custom property to adjust how frequently the core group IP cache is cleared.

The caching of name-to-IP address information at the core group level eliminates some of the system overhead required to assign IP addresses to core group members.

Table 5. Units, default, and acceptable values. The following table describes the units, default, and acceptable values for the setting.
Units Minutes
Default 1
Acceptable values Any positive integer. 1 is the minimum value that can be specified

To set a value for this custom property, in the administrative console, click Servers > Core Groups > Core group settings > core_group_name. Then, under Additional Properties, click Custom properties.

IBM_CS_OOM_ACTION

Use this custom property to explicitly enable exception handlers that are specific for OutOfMemoryError exceptions that occur when sending or receiving network messages. When this property is set to Isolate, if an OutOfMemoryError exception occurs when a network message is being sent or received, the value of this property is displayed in the logs and these exception handlers stop High Availability Manager communications to the Out of Memory process.

If IBM_CS_OOM_ACTION=Isolate is not added to the configuration settings for a core group, if a core group process runs out of memory, the Out of memory process might not be able to respond to all messages. This situation prevents multi-step protocols from completing, and prevents the starting server from receiving its initial view of the distributed state.

IBM_CS_SOCKET_BUFFER_SIZE

Use this custom property to change the size of the socket buffer that the core group transport obtains.

Configuring core group socket buffers includes a table that shows the relationship between the values that can be specified for this property and the underlying memory allocation size per socket buffer type.
Table 6. Units and default. The following table describes the units and default for the setting.
Information Value
Units One of the following:
  • No over rides
  • small
  • medium
  • large
Default 2 megabytes for all buffer types.

To set a value for this custom property, in the administrative console, click Servers > Core Groups > Core group settings > core_group_name. Then, under Additional Properties, click Custom properties.

IBM_CS_UNICAST_DISCOVERY_INTERVAL_SECS

This custom property is used to change how frequently the high availability manager Discovery Protocol checks for new core group members. A new core group member is not able to communicate with other core group members until the Discovery Protocol establishes communication between the new member and the existing members.

Deprecated feature: This custom property is deprecated. Do not use this custom property unless you are running in a mixed cell environment that includes at least one core groups that contains a mixture of Version 7.0 and Version 6.x processes.

However, you can also use the Discovery and failure detection page in the administrative console to change how frequently the high availability manager Discovery Protocol checks for new core group members. Unless you are running in a mixed cell environment, using the administrative console is the preferred technique for updating this setting because the IBM_CS_UNICAST_DISCOVERY_INTERVAL_SECS property is deprecated.

Mixed-version environment: If you are running in a mixed cell environment, and you have core groups that contain a mixture of Version 7.0 and Version 6.x processes, you must continue to use the IBM_CS_UNICAST_DISCOVERY_INTERVAL_SECS core group custom property to change how frequently the Discovery Protocol attempts to open a new network.
Table 7. Units and default. The following table describes the units and default for the setting.
Units Seconds
Default 30

To set a value for this custom property, in the administrative console, click Servers > Core Groups > Core group settings > core_group_name. Then, under Additional Properties, click Custom properties.

IBM_CS_WIRE_FORMAT_VERSION

Use this custom property to configure all of the members of the selected core group to run with a different version of the core group protocol. You can change the value of this property while the core group members continue to run. After you save and synchronize the changed value to all of the nodes containing core group processes, the high availability manager automatically detects the configuration change and starts using the new core group protocol version to communicate with the core group members.

Deprecated feature: Protocol versions 6.0.0 and 6.0.2.9 are deprecated. Whenever possible you should use a newer protocol version.
Table 8. Supported core group protocol version IDs. The following table lists the supported core group protocol version IDs. 6.0.0 is the default value.
Version ID Required Minimum Product Level Description
6.0.0 6.0.0.0 for Version 6.0, 6.1.0.0 for Version 6.1, 7.0.0.0 for Version 7.0 This protocol version is the original or base version. All versions of the high availability manager can use this protocol version. If you do not specify a particular protocol version the high availability manager uses this version.
6.0.2.9 6.0.2.9 for Version 6.0.2, 6.1.0.0 for Version 6.1, 7.0.0.0 for Version 7.0. This protocol version was included in the 6.0.2.9 service pack, and in Versions 6.1, and 7.0 of the product to facilitate core group bridge scalability. This version is recommended for large topologies that contain multiple core groups and core group bridges as part of their configuration.
6.1.0 6.1.0.0 for Version 6.1, 7.0.0.0 for Version 7.0 This protocol version was included in Versions 6.1, and 7.0 of the product to add core group scalability improvements, and more support for large topologies.

You can set this custom property to the values that are listed in the Version ID column of the previous table. Set the value to the most current value that is possible for your environment.

To set a value for this custom property, in the administrative console, click Servers > Core Groups > Core group settings > core_group_name. Then, under Additional Properties, click Custom properties.