Configuring core group memory utilization

You can use the administrative console to control the maximum amount of heap memory that is available for the underlying core group transport to allocate.

Before you begin

You should understand the following information:

  • Other factors, such as the number of network interface cards on a machine, how the Network interface card is used, and network speed, can affect the memory that the high availability manager requires to efficiently handle network messages
  • The amount of memory that the high availability manager controls as it sends network messages varies. Typically, the high availability manager retains control of this memory for only short lengths of time.
  • The default setting of 100 MB is typically sufficient for most network deployment topologies.
  • The maximum value for this setting is the size of the Java™ heap.
  • In core groups that contain both Version 6.x and Version 7 processes, all memory settings must Be Equal. The default memory setting for Version 6.x processes is 10 MB. Therefore, you must adjust either the Version 6.x or the Version 7 setting to make both settings equal.

About this task

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.

The high availability manager consumes its allocated heap memory when it sends interprocess messages on behalf of other services that use the high availability manager functions. For example, the heap memory might be consumed while sending memory-to-memory replication data, or highly available routing data from one core group member to another core group member.

The value that you specify for the Transport memory size property acts as a flow control mechanism that might affect the speed at which data is replicated or the speed at which routing data is made available to other core group members.

Therefore, you might want to perform this task if you are seeing large numbers of any of the following Distribution and Consistency Services (DCS) congestion messages in your SystemOut.log file: 
DCSV1051W, a high severity congestion event for outgoing messages
DCSV1052W, a medium severity congestion event for outgoing messages
DCSV1054W, a medium severity congestion event for incoming messages

Under extreme workloads, these messages might still occur on a properly tuned system.

Mixed-version environment: If you are running in a mixed cell environment, you must continue to use the following two memory configuration attributes to configuring core group memory utilization for the Version 6.x cells:
  • The Transport buffer size property, which is set for each individual core group member. To specify a value for this property, in the administrative console, navigate one of the following paths:
    • If the core group member is an application server, click Servers > Server Types > WebSphere application servers > server_name > Core group service.
    • If the core group member is a node agent, click System Administration > Node agents > node_agent_name > Core group service.
    • If the core group member is a deployment manager, click System Administration > Deployment manager > Core group service.
  • The IBM_CS_DATASTACK_MEG custom property. To specify a value for this custom property, in the administrative console, click Servers > Core Groups > Core group settings > core_group_name > Custom properties.

To change the amount of memory that is available for in-flight messages and network communication buffers, complete the following steps:

Procedure

  1. In the administrative console, click Servers > Core Groups > Core group settings > core_group_name.
  2. Change the setting for the Transport memory size property.

    This property, specifies in megabytes, the maximum amount of heap memory that can be allocated to the high availability manager. The maximum value that can be specified for the transport memory size property is the size of the Java™ heap.

    For transitioning users: This property includes the functionality of the Transport buffer size property that exists for Version 6.x cells.
  3. Click OK.
  4. Click Review to review your changes.
  5. Select Synchronize changes with Nodes, and then click Save to save your changes.
  6. Restart all members of the core group.

Results

After the servers restart, they all run with the new memory settings.