The core group bridge service can be configured for communication
between core groups. Use an access point group to define the core groups that
communicate. Use this task to configure communication between core groups
that are in different cells.
About this task
Use the core group bridge service to share the availability status
of the servers in each core group among all the configured core groups. Enable
the core group bridge only when the service is required by a WebSphere Application
Server component.
For example, the core group
bridge is required when configuring an Enterprise JavaBeans (EJB) backup cluster.
Configure a backup EJB cluster in a different cell to continue servicing requests
when the primary cluster fails. See Creating backup clusters for more information.
When you configure core group
communication between core groups that are in different cells, you must configure
an access point group to connect the core groups. The name of the access point
group must be the same in all of the connected cells. This task uses the DefaultAccessPointGroup
access point group, but you can create and use another access point group.
You can define
the CGB_ENABLE_602_FEATURES custom property on all of the access point groups
in your configuration if you want to be able to add core group bridge servers
to the configuration without restarting the other servers in the configuration.
After you enable this property, you can add a core group bridge server in
one cell, without modifying the configuration in the other cell to include
peer ports for the core group bridge server. Instead of manually configuring
peer ports in each of the cells, you can configure the peer ports in one cell
and let the other cell discover the peer ports for the first cell.
If
you decide to use the CGB_ENABLE_602_FEATURES custom property, you must decide
which cell is the listener cell and which cell initiates contact with the
other cells before you begin your configuration. The listener cell does not
need to contain any peer access points or peer ports for the other cells in
the configuration. For example, in a configuration that contains a secured
cell and an unsecured cell, configure the unsecured cell as the listener.
The unsecured cell cannot access information about the secured cell. Configure
the core group bridge service on the listener cell first.
Attention: Do not configure the CGB_ENABLE_602_FEATURES
custom property if you already configured the FW_PASSIVE_MEMBER custom property.
Any server for which the configured the FW_PASSIVE_MEMBER custom property
is configured cannot initiate contact with other systems in the configuration.
For more information about the FW_PASSIVE_MEMBER custom property, see
Core group bridge custom properties.
Avoid trouble: When configuring core group bridges, remember the following requirements:
- Whenever a change is made in core group bridge configuration, including
the addition of a new bridge, or the removal of an existing bridge, you must
fully shutdown, and then restart all core group bridges in the affected access
point groups.
- There must be at least one running core group bridge in each core group.
Configuring two bridges in each core group, allows for single failures, and
the periodic cycling out of one bridge at a time from each core group. If
all the core group bridges in a core group are shutdown, core group state
from all foreign core groups is lost.
gotcha
Best practice: It
is also recommended that:
- Core group bridges be configured in their own dedicated server process,
and that these processes have their monitoring policy set for automatic restart.
- For each of your core groups, you set the IBM_CS_WIRE_FORMAT_VERSION core
group custom property to the highest value that is supported on your environment.
bprac
Complete
the following set of steps for each of the cells in your configuration.
- Configure bridge interfaces for your core group access point.
Configuring a bridge interface indicates that the specified node, server,
and chain combination is a core group bridge server. This node and server
use the specified chain to communicate with other core groups.
- In the administrative console, click Servers
> Core groups > Core group bridge settings > Access point groups > DefaultAccessPointGroup >
Core group access points > CGAP_1\DefaultCoreGroup > Show detail
> Bridge interfaces > New.
- Select a node, server, and transport channel chain that becomes
your bridge interface.
- Click Apply.
- Repeat this set of steps to add more bridge interfaces to the
core group access point. Define at least two bridge interfaces
for each core group access point to back up your configuration. By defining
two bridge interfaces, you define two core group bridge servers. If one core
group bridge server fails, the other can take over the work so that the communication
between the core groups can continue.
Important:
The bridge
interfaces that you select must all have the same transport channel chain.
- If you want the ability to add core group
bridge servers to the configuration without restarting the other servers in
the configuration, define the CGB_ENABLE_602_FEATURES custom property on all
of the access point groups in your configuration.
- In the administrative console, click Servers > Core groups
> Core group bridge settings > Access point groups > DefaultAccessPointGroup >
Custom properties > New.
- Type the name as CGB_ENABLE_602_FEATURES and set the value to
any string.
The existence of the CGB_ENABLE_602_FEATURES
property enables the property. Therefore, you can set the value to any string
value. Setting the value to false does not disable the
property. To disable the property, you must remove it from the list of defined
custom properties or change its name.
- Click Apply and save your configuration.
When you complete this step on all the access point groups
in your configuration, you can add a bridge interface to one of the cells.
You can save the configuration so that it is propagated to all of the nodes.
Instead of restarting all of the application servers, you need to restart
the new bridge interface server only.
- Add peer access points and peer ports to your access point group.
If you defined the CGB_ENABLE_602_FEATURES
custom property for all of the access point groups in your configuration,
you do not need to add peer access points or peer ports to the listener cell.
Add
a peer access point for each core group that is in another cell. Within each
peer access point, you should configure a peer port that corresponds to each
bridge interface in the other cell. Before you add a peer access point, you
should have the following information about the other cell:
- cell name
- core group name
- core group access point name
- host and port information. The host and port correspond to the bridge
interfaces that are configured in the other cell. Specify a peer port for
each bridge interface that is in the other cell.
- In the administrative console, click Servers > Core groups
> Core group bridge settings > Access point groups > DefaultAccessPointGroup >
Peer access points > New.
- Specify the information for your peer access point and click Next.
- Select Use peer ports. Specify the host and port information
for your peer cell. For example, if you defined a bridge interface
in cell_x, use that configuration information for your peer port in cell_y.
- Click Next and then Finish. Save your configuration.
If more than one bridge interface is defined in your peer cell, add
additional peer ports for each bridge interface.
- Click Peer_access_point_name > Show detail > Peer ports >
New.
- Enter the host name and port.
- Click Apply and save your changes.
- Optional: Configure the high availability
manager protocol to establish transparent bridge failover support.
During
core group bridge state rebuilds, cross-core group state can be moved between
running bridges. This situation might cause the data to be temporarily unavailable
until the bridge has completed the rebuild process.
If
you are running on Version 6.1.0.19 or later, set the IBM_CS_HAM_PROTOCOL_VERSION
core group custom property to 6.0.2.31 for all of
your core groups to avoid a possible high availability state outage during
core group bridge failover. When this custom property is set to 6.0.2.31,
the remaining bridges recover the high availability state of the failed bridge
without the data being unavailable in the local core group.
Complete
the following actions to set the IBM_CS_HAM_PROTOCOL_VERSION core group custom
property to 6.0.2.31 for all of your core groups.
- Shut down all core group bridges in all of your core groups.
- Repeat the following actions for each core group in each of
your cells:
- In the administrative console, click core_group_name >
Custom properties.
- Specify IBM_CS_HAM_PROTOCOL_VERSION in the Name field,
and 6.0.2.31 in the Value field.
- Save your changes.
- Synchronize your changes across the topology.
- Restart all of the bridges in the topology.
All of the core groups within this topology are using the 6.0.2.31
high availability manager protocol.
Example
The following illustration is an example of a configuration between
two core groups that are in two different cells. Each cell has a defined DefaultAccessPointGroup access
point group, which contains one core group access point for the core group
that is in the cell and a peer access point for the other cell.