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Core group custom properties

To set...

When we set the core group custom properties, make sure that the core group or the cell is in a stable state. We do not want to set these custom properties when we are simultaneously starting or stopping servers. Also, ensure that the high availability manager is in a known, good state. Below are best practices for some specific core group custom properties:

IBM recommends using the High Performance Extensible Logging (HPEL) log and trace infrastructure . We view HPEL log and trace information using the logViewer .


IBM_CS_DATASTACK_MEG

Eliminate a condition that is reported by a message displayed repeatedly in SystemOut.log.

Deprecated feature: This custom property is deprecated. Do not use this custom property unless we are running in a mixed cell environment that includes at least one core groups containing a mixture of v7.0 and v6.x processes.depfeat

Mixed-version environment: If we are running in a mixed cell environment, and we have core groups that contain a mixture of v7.0 and v6.x processes, we 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.

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

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

We can also set this custom property:

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

Units Megabytes
Default 5


IBM_CS_FD_CONSECUTIVE_MISSED

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 we are running in a mixed cell environment that includes at least one core group containing a mixture of v7.0 and v6.x processes.depfeat

However, we 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 we 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 we are running in a mixed cell environment, and we have core groups that contain a mixture of v7.0 and v6.x processes, we 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. mixv

Units Seconds
Default 6


IBM_CS_FD_PERIOD_SECS

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 we are running in a mixed cell environment that includes at least one core group containing a mixture of v7.0 and v6.x processes.depfeat

However, we 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 we 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 we are running in a mixed cell environment, and we have core groups that contain a mixture of v7.0 and v6.x processes, we 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. mixv

Units Seconds
Default 6


IBM_CS_HAM_PROTOCOL_VERSION

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. We can change the value of this property while the core group members continue to run. After saving and synchronizing 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.

Version ID Required Minimum Product Level Description
6.0.2.31 6.0.2.31 for v6.0, 6.1.0.19 for Version 6.1, 7.0.0.1 for v7.0 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

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.

Units Minutes
Default 1
Acceptable values Any positive integer. 1 is the minimum value that can be specified


IBM_CS_OOM_ACTION

Enable exception handlers specific for OutOfMemoryExceptions that occur when sending or receiving network messages. When set to Isolate, if an OutOfMemoryException 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. This is now the default action and there is no need to explicitly set this property to Isolate.

This custom property can be used to change the out of memory action. Valid actions are Terminate which stops the JVM when an OutOfMemoryException occurs, and Ignore. If the IBM_CS_OOM_ACTION=Ignore custom property is added to the configuration settings for a core group and if a core group process runs out of memory that 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

Change the size of the socket buffer that the core group transport obtains.

Configure 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.

Information Value
Units
  • No over rides
  • small
  • medium
  • large

Default 2 megabytes for all buffer types.


IBM_CS_UNICAST_DISCOVERY_INTERVAL_SECS

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 we are running in a mixed cell environment that includes at least one core group containing a mixture of v7.0 and v6.x processes.depfeat

However, we 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 we 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 we are running in a mixed cell environment, and we have core groups that contain a mixture of v7.0 and v6.x processes, we 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.mixv

Units Seconds
Default 30


IBM_CS_WIRE_FORMAT_VERSION

Configure all of the members of the selected core group to run with a different version of the core group protocol. We can change the value of this property while the core group members continue to run. After saving and synchronizing 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.

When we set this custom property to 6.1.0, the value is automatically detected and applied to all nodes. We do not need to stop or start servers. Setting this property value in a topology in which only a single core group exists does not provide any benefit. However, if we 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 starting the bridges. If our topology contains multiple core groups that are bridged together, set this value to the most current possible version.

Deprecated feature: Protocol versions 6.0.0 and 6.0.2.9 are deprecated. Whenever possible we should use a newer protocol version.depfeat

Version ID Required Minimum Product Level Description
6.0.0 6.0.0.0 for v6.0, 6.1.0.0 for Version 6.1, 7.0.0.0 for v7.0 This protocol version is the original or base version. All versions of the high availability manager can use this protocol version. If we do not specify a particular protocol version the high availability manager uses this version.
6.0.2.9 6.0.2.9 for v6.0.2, 6.1.0.0 for Version 6.1, 7.0.0.0 for v7.0. 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 v6.1, 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.

Set the values listed in the Version ID column of the previous table. Set the value to the most current value that is possible for the environment.


Related:

  • Core group discovery and failure detection protocols
  • Change the number of core group coordinators
  • Use High Performance Extensible Logging to troubleshoot applications