Creating a new core group (high availability domain)

A default core group, called DefaultCoreGroup, is created for each cell. This default core group or high availability domain as it is sometimes referred to, is sufficient in most configurations. However there are some circumstances under which you need to create additional core groups for a cell.

Before you begin

Determine how to segment your existing cell into multiple core groups. Use the following rules as guidelines:

All members of a cluster must be in the same core group. A core group can contain multiple clusters.
Core group members cannot cross firewall boundaries.
Put clusters with direct relationships in the same core group. Examples of direct relationships include:
- A single application is deployed on multiple clusters.
- An application on one cluster calls an application on another cluster.

Best practice: You should also try to keep your core groups homogeneous. If your installation topology requires you to set up a mix of processes that use and do not use the high availability manager, you can:

Create a new core group and move all application servers for which the high availability manager is disabled to this core group. A core group that is not managed by a high availability manager does not have a size limit.
Leave the remaining applications servers that require high availability manager services in the default core group. If the number of application servers remaining in the default core group is too large for the high availability manager to handle efficiently, create another core group, and move some of these application servers into that core group.

About this task

You might want to add another core group to a cell if you are scaling up the number of servers in a cell. Multiple core groups are recommended for a large cell.

To create a new core group:

Procedure

In the administrative console, click Servers > Core Groups > Core group settings > New .
In the Name field, specify a unique name for the new core group.
The name can contain alpha and numeric characters, but not the following special characters:
```
#  \  /  ,  :  ;  "  *  ?  <  >  |  =  +  &  %  ' 
```
The name also cannot begin with a period (.) or a blank space. A blank space does not generate an error. However, leading and trailing blank spaces are automatically deleted from the name.
Add a description of this core group that helps other administrators understand the purpose of this core group.
Click OK and then click Review.
Select Synchronize changes with nodes, and then click Save.

Results

The cell contains another core group.

What to do next

You must now:

Complete your core group configuration. The initial core group settings and policies are derived from a template. If the settings from the default template do not meet your requirements, you can:
- Change the number of coordinators for this core group.
- Change the transport type for this core group.
- Add policies for this core group.
Move members to the new core group.
Create bridges between core groups. If clusters with direct relationships are not in the same core group, set up a core group bridge to connect the related core groups.