Configuring multi-cell performance management: Star Topology

Configure and manage multi-cell performance in your environment to avoid overprovisioning resources, such as CPU and memory utilization. Adding or removing cells to a star topology is completely dynamic. However, the center cell has to be restarted after the CenterCell=true custom property is set.

Before you begin

Create and configure the cells that communicate with each other. Ensure that system clocks are in sync across all participating cells in Center and Point cells.

About this task

When you configure multi-cell performance management, multiple cells are managed as a single unit, because the cells share common resources. From a functional perspective, performance management, such as dynamic clusters and overload protection, operates on multiple cells of the same hardware in the same way that performance management operates in a single cell. This feature applies directly to the application placement controller to allow management, through dynamic placement and elasticity, throughout the topology.

In a star topology a single cell is designated as the center cell, while the other cells are designated as the point cells. The center cell can perform work, such as contain ODRs and application servers, and only the center cell makes autonomic decisions to start or stop application servers.

Indications for the star topology include:

For the consolidation of ODRs, ODRs in a single center cell can route to application servers in multiple point cells.
A star topology can help manage performance in server virtualized environments where multiple cells share the same hardware resources. A single Application Placement Controller (APC) in the center cell can manage the performance of all cells in the star topology by starting and stopping application servers in point cells to meet current demand.

The following procedure describes a sample scenario in which multi-cell performance management is configured in a star topology environment so that work requests can be routed from an ODR to dynamic cluster members across cells. The ODR is installed and running on CellA, which is the center cell. The two-point cells, CellB and CellC, contain the dynamic clusters and applications.

Avoid trouble: Complete either the automatic step or the manual step to configure multi-cell performance management. Do not complete both steps.

Procedure

Automatically configure multi-cell performance management.
1. Set the following custom property to designate CellA as the center cell.
  1. In the administrative console, select System administration > Cell > Custom properties > New.
  2. Specify the name of the custom property as CenterCell.
  3. Specify the value of the custom property as true.
  4. Click OK, and save and synchronize your changes.
  Avoid trouble: Set only one custom property to true.
2. Set the following custom property individually for each cell that you want to designate as a point cell. In this sample scenario, complete steps 2a through 2c to designate CellB as one-point cell. Next, repeat steps 2a through 2c to designate CellC as another point cell.
  1. In the administrative console, select System administration > Cell > Custom properties > New.
  2. Specify the name of the custom property as CenterCell.
  3. Specify the value of the custom property as false.
  4. Click OK, and save and synchronize your changes.
3. Restart all the cells.
  Note: Restart the center cell only if the CenterCell=true custom property is initially set. If you link additional cells, restart only the additional cells.
4. If global security is enabled, in the administrative console, go to Security > SSL certificate and key management. Select the check box to dynamically update the run time when SSL configuration changes occur. Sync the nodes on all cells.
5. Run the linkCells.sh script from CellA to configure the overlay communication between the cells. The linkCells.sh script is available in the install_root/bin directory. Run the script to link the center cell with each point cell individually. Do not link point cells together.
  Note: Run the linkCells.sh script from the cell with the oldest product version.
```
./linkCells.sh CellA_deployment_manager_host:CellA_soap_port:user_id:password CellB_deployment_manager_host:
  CellB_soap_port:user_id:password
```
```
./linkCells.sh CellA_deployment_manager_host:CellA_soap_port:user_id:password CellC_deployment_manager_host:
  CellC_soap_port:user_id:password
```
  On z/OS systems, run the linkCellsZOS.sh script from CellA to configure the overlay communication between the cells. The linkCellsZOS.sh script is available in the install_root/bin directory. Run the script to link the center cell with each point cell individually. Do not link point cells together.
  Note: Run the linkCellsZOS.sh script from the cell with the oldest product version.
```
./linkCellsZOS.sh CellA_deployment_manager_host:CellA_soap_port:user_id:password CellB_deployment_manager_host:
  CellB_soap_port:user_id:password
```
```
./linkCellsZOS.sh CellA_deployment_manager_host:CellA_soap_port:user_id:password CellC_deployment_manager_host:
  CellC_soap_port:user_id:password
```
Manually configure multi-cell performance management.
1. Set the following custom property to designate CellA as the center cell.
  1. In the administrative console, select System administration > Cell > Custom properties > New.
  2. Specify the name of the custom property as CenterCell.
  3. Specify the value of the custom property as true.
  4. Click OK, and save and synchronize your changes.
  Avoid trouble: Set only one custom property to true.
2. Set the following custom property individually for each cell that you want to designate as a point cell. In this sample scenario, complete steps 2a through 2c to designate CellB as one-point cell. Next, repeat steps 2a through 2c to designate CellC as another point cell.
  1. In the administrative console, select System administration > Cell > Custom properties > New.
  2. Specify the name of the custom property as CenterCell.
  3. Specify the value of the custom property as false.
  4. Click OK, and save and synchronize your changes.
3. If global security is enabled, in the administrative console, go to Security > SSL certificate and key management. Select the check box to dynamically update the run time when SSL configuration changes occur. Sync the nodes on all cells.
4. Configure the overlay communication between the cells. Run the importOverlayConfig.py script, and specify the overlaynodes.config file of each cell. The overlaynodes.config file is in the WAS_HOME/profiles/deployment_manager_profile_name/config/cells/cell_name directory of each cell.
  - Run the importOverlayConfig.py script from the deployment manager on CellA to link the overlay anchor transports of CellA to CellB. Specify the path to the overlaynodes.config file of CellB.
```
WAS_HOME/bin/wsadmin.sh -profileName profile_name -f importOverlayConfig.py 
  link path_to_CellB_overlaynodes.config_file
```
  - Run the importOverlayConfig.py script from the deployment manager on CellA to link the overlay anchor transports of CellA to CellC. Specify the path to the overlaynodes.config file of CellC.
```
WAS_HOME/bin/wsadmin.sh -profileName profile_name -f importOverlayConfig.py 
  link path_to_CellC_overlaynodes.config_file
```
  - Run the importOverlayConfig.py script from the deployment manager on CellB to link the overlay anchor transports of CellB to CellA. Specify the path to the overlaynodes.config file of CellA.
```
WAS_HOME/bin/wsadmin.sh -profileName profile_name -f importOverlayConfig.py 
  link path_to_CellA_overlaynodes.config_file
```
  - Run the importOverlayConfig.py script from the deployment manager on CellC to link the overlay anchor transports of CellC to CellA. Specify the path to the overlaynodes.config file of CellA.
```
WAS_HOME/bin/wsadmin.sh -profileName profile_name -f importOverlayConfig.py 
  link path_to_CellA_overlaynodes.config_file
```
5. Exchange the root certificates between the cells. Complete the following steps multiple times to extract and copy the root certificate of CellA to each point cell, and to extract and copy the root certificate of each point cell to CellA.
  1. In the administrative console, select Security > SSL certificate and key management > Key stores and certificates.
  2. Select Root certificates keystore from the Keystore usages menu. A new panel is displayed. Click CellDefaultTrustStore.
  3. Select Personal certificates from the list of Additional properties, select the root certificate, and click Extract.
  4. Specify the fully qualified path to where the file is stored on the deployment manager in the Certificate file name field, for example /tmp/myrootcertificate. Click OK.
  5. Save and synchronize your changes.
  6. Copy the root certificate to the deployment manager of the target cell.
6. Specify the location of each root certificate between the cells. Complete the following steps multiple times to specify the location of the root certificate of CellA to each point cell, and to specify the location of the root certificate of each point cell to CellA. In this example, the location of the root certificate of CellA is specified in the administrative console of CellB.
  1. In the administrative console of CellB, select Security > SSL certificate and key management > Key stores and certificates > CellDefaultTrustStore.
  2. Select Signer certificates from the list of Additional properties. A new panel is displayed. Click Add.
  3. Specify the location of the root certificate on the deployment manager of CellA, and click OK.
  4. Save and synchronize your changes.
7. If you installed middleware agents in the cells, add the middleware agents to the root certificates. Complete steps 7a through 7f for each and every cell.
  1. In the administrative console, select Security > SSL certificate and key management > Key stores and certificates > NodeDefaultKeyStore > Personal certificates > Create > Chained certificate
  2. Enter the name of the middleware agent in the Alias and Common name fields, and click OK.
  3. Save and synchronize your changes.
  4. Replace the default self-signed certificate with the new certificate. Select the default self-signed certificate from the table, and click Replace
  5. Select the Delete old certificate after replacement check box, verify that the name of the new certificate is displayed in the Replace with field, and click OK.
  6. Save and synchronize your changes.

Results

You configured multi-cell performance management for your environment so that you can manage your cells as a single unit. You did the configuration by using either the automatic step or the manual step.