Configure a core group for replication

 

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Overview

WAS administrators can control the maximum amount of heap memory that the underlying core group transport can allocate. This memory is used for in-flight messages and network communication buffers. If you increase the maximum amount of heap memory that the transport can allocate, also increase the size of the transport buffer accordingly.

• Understand that 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 replication throughput performance.

• Determine the maximum amount of memory that you can let the core group transport allocate for buffering incoming messages. The default value is 10 megabytes. You can increase this value as required to allow for buffering of additional incoming messages. A setting of 100 is sufficient for most high throughput topologies.

You might want to perform this task if:

• You are trying to tune your systems replication performance.

• 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.

To change amount of memory that is available for in-flight messages and network communication buffers:

 

Procedure

1. Change the value of the IBM_CS_DATASTACK_MEG custom property.

   The value specified for the IBM_CS_DATASTACK_MEG custom property has a strong impact on the message throughput of a replication domain. The setting for this property controls the amount of memory that the data stack can use. The default value for this property is 50 megabytes.

   A replication domain that handles high throughput messaging, needs this property set to a higher value. The maximum value for this property is 256 megabytes.

   A setting of 100 megabytes is sufficient for most high throughput topologies.

   1. In the console, click...

      Servers | Core groups | Core group settings | core_group_name | Additional Properties | Custom Properties

   2. Change the value specified for the IBM_CS_DATASTACK_MEG custom property.

      If the IBM_CS_DATASTACK_MEG property already exists, click on the property name and, in the Value field, specify the maximum amount of memory to let the core group transport allocate for buffering incoming messages.

      If this property does not already exist, click New and then:

      1. In the Name field, specify IBM_CS_DATASTACK_MEG.

      2. In the Value field, specify the maximum amount of memory you want to let the core group transport allocate for buffering incoming messages.

   3. Click OK, and then click Save to save your changes.

2. Change the size of the transport buffer. The maximum amount of heap memory that is specified for the IBM_CS_DATASTACK_MEG custom property should be less than or equal to the size of the transport buffer.

   1. In the console, click...

      Servers | Application servers | server | Additional Properties | Core group service

   2. In the Transport buffer size field, specify, in megabytes the size of the transport buffer.

   3. Click OK.

   4. Repeat the previous three steps for all of the appservers that are members of this core group. Specify the same transport buffer size for all of these core group members.

   5. Click...

      System administration | Node agents | node_agent_name | Additional properties | Core group service

   6. In the Transport buffer size field, specify, in megabytes the size of the transport buffer.

   7. Click OK.

   8. Repeat the previous three steps for all of the node agents that are members of this core group.

   9. Click...

      System administration | Deployment Manager | Additional properties | Core group service

   10. In the Transport buffer size field, specify, in megabytes the size of the transport buffer.

3. Click Review to review your changes.

4. Select Synchronize changes with Nodes, and then click Save to save your changes.

5. Restart all members of the core group.

 

Results

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

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Related concepts

Core groups (high availability domains)

 

Related tasks

Setting up a high availability environment