Installing and starting the Zowe high availability started task (ZWESLSTC)

Zowe has a number of runtimes on z/OS: the z/OS Service microservice server, the Zowe Application Server, and the Zowe API Mediation Layer microservices. In a high availability environment, a single PROCLIB member ZWESLSTC is used to start multiple instances of a same component. This member is installed by Zowe into the SAMPLIB data set SZWESAMP during the installation from either a convenience build or an SMP/E build.

This topic describes how to configure the z/OS runtime in order to launch Zowe for high availability instances. You can do these manually (as described in this topic) or use script to install and configure the Zowe launcher server. See Installing and Configuring Zowe z/OS components using scripts.

Step 1: Copy the PROCLIB member ZWESLSTC

Zowe high availability instances are run under a z/OS started task with the PROCLIB member named ZWESLSTC. A sample PROCLIB member is created during installation into the PDS SZWESAMP(ZWESLSTC). To launch high availability instances as a started task, you must copy this member to a PDS that is in the PROCLIB concatenation path.

Step 2: Configure ZWESLSTC to run under the correct user ID

ZWESLSTC should be configured as a started task under the ZWESVUSR user ID with the administrator user ID of ZWEADMIN. If you do not have these IDs already created, you can find the commands to create the user ID and group in the PDS member ZWESECUR. See Configuring the z/OS system for Zowe. To associate the ZWESLSTC started task with the user ID and group, see Configuring a z/OS system for Zowe. This step is done once per z/OS environment by a system programmer who has sufficient security privileges.

Step 3: Launch the ZWESLSTC started task

You launch the ZWESLSTC started task with the z/OS START command.

Before you begin

Before starting ZWESLSTC, you need to perform the following steps in PROCLIB member ZWESLSTC:

1. Set the parameter INSTANCE_DIR to the location (fully qualified path) of the Zowe instance directory that contains the zowe.yaml configuration file.
2. Update the STEPLIB DD statement with the location of the load library that contains the load module ZWELNCH.

Procedure

You can start Zowe high availability instances by issuing the command S ZWESLSTC in SDSF. When you issue S ZWESLSTC, you must specify which high availability instance you want to launch by adding the HAINST parameter on the START command:

S ZWESLSTC,HAINST=<ha-instance-id>

where, the ha-instance-id argument is the high availability instance ID that is defined in the haInstances section of the zowe.yaml configuration file. To learn more about zowe.yaml, see the Updating the zowe.yaml configuration file section.

This command enables you to start multiple instances of a same component, which eliminates single point of failure to ensure continuous operation of Zowe components.

• If you want to have more than one Zowe high availability instance running concurrently, use the optional parameter JOBNAME with the START command to distinguish the Zowe high availability instances from each other.

  S ZWESLSTC,HAINST=<ha-instance-id>,JOBNAME=<instance-job-name>

• Zowe Launcher also enables you to restart a specific component of a high availability instance by using z/OS MODIFY command:

  F ZWESLSTC,APPL=START(<ha-component-name>)

  where, the ha-component-name argument is the high availability instance component that is defined in the components section of zowe.yaml configuration file. To learn more about zowe.yaml, see the Updating the zowe.yaml configuration file section.

• If you specified the JOBNAME= parameter on the START command, the instance-job-name can be used with MODIFY command to restart a specific component:

  F <instance-job-name>,APPL=START(<ha-component-name>)

Next steps

To check whether the ZWESLSTC started task has successfully launched, see Troubleshooting installation and startup of Zowe z/OS components for instructions.