Q: What are the benefits of z/OS Container Extensions?

A: z/OS Container Extensions expands and modernizes the z/OS software ecosystem to include Linux on IBM Z applications. Most applications (including Systems Management components and development tools) that are currently only available to run on Linux will be able to run on z/OS as Docker containers. zCX runs Linux on IBM Z applications on z/OS, using existing z/OS operations staff and reusing the existing z/OS environment. zCX maintains operational control within z/OS and z/OS Qualities of Service (scalability, availability, integrated disaster recovery, backup, WLM, and integration with z/OS security).

Q: How is Container Extensions different from Linux on IBM Z?

A: zCX gives z/OS environments the ability to deploy Linux on IBM Z applications as Docker containers for workloads with an affinity to z/OS. It is not a replacement for traditional Linux on IBM Z environments.

If you are a client with Linux on IBM Z installations, you will continue to run those installations. If you are a z/OS client that used to, but no longer has a Linux on IBM Z installation, you should consider zCX. If you are a z/OS client that has never had a Linux on IBM Z installation, then zCX Extensions is a low effort way to try Linux on IBM Z.

Q: How can I remove the IBM Container Hosting Foundation for z/OS (5655-HZ1) entitlement requirement to use zCX?

A: Apply APARs OA66764, OA66765 and related APARs for the FMID HZDC7C0 (z/OS Container Extensions), and upgrade all existing zCX instances to the zCX 2.0 maintenance level using the zCX z/OSMF upgrade workflow. If your existing zCX instances are at version 1.25 or earlier, then you need to upgrade to version 1.26 first before upgrading to zCX 2.0. See Release notes for APAR information. Once all upgrades are successful and all zCX instances are successfully restarted, you can safely disable and remove the IBM Container Hosting Foundation for z/OS (5655-HZ1) product registration in the IFAPRDxx member.

Q: What are some zCX use cases?

A: z/OS software ecosystem expansion: Latest microservices, non-SQL databases, analytics frameworks, ICP, application server environment, and emerging programming languages and environments.

Systems management: Centralization of UI portals for management products and databases
z/OS modernization: Open source application development utilities.

Q: Are there samples and resources that I can look at to get started?

A: Yes. Visit the Open Mainframe Project, Ambitus, for samples, build recipes, and other resources to promote collaboration and knowledge sharing of open source technologies to modernize and expand the IBM Z platform.

Open Mainframe Project Ambitus

Q: Do application developers require knowledge of z/OS to create and deploy Linux on IBM Z applications to run in z/OS Container Extensions?

A: Applications will look like Docker applications to the developer, not z/OS applications. If your application comes from Linux on IBM Z, then no z/OS skills are required. Docker and Linux knowledge are all that is required.

Q: Does Container Extensions make use of Kubernetes?

A: No, not at this time. The initial release of zCX for IBM z/OS V2.4 provides Docker Swarm as support for Docker cluster management. IBM’s future plans intend to include Kubernetes clustering for the orchestration, scalability, and management of zCX with compatible cloud platforms.

Q: Will there be performance data published for zCX?

A: There is currently no plan to publish performance data for the zCX environment because performance is heavily reliant on individual configuration, workload, and networking characteristics.

Q: What are the costs associated with z/OS Container Extensions?

A: zCX is a base element of z/OS. There is no additional software cost for zCX itself beyond z/OS. Associated costs are possible hardware costs for zIIPs and any software licensing of Linux on IBM Z applications running inside zCX.

Q: On which engine types can z/OS Container Extensions run?

A: z/OS Container Extensions address spaces are zIIP-eligible. Most zCX processing (including Docker containers deployed within zCX) can be dispatched on available zIIP processors. Some zCX processing will be dispatched on standard processors. This will generally be a much smaller percentage of processor cycles compared to what can execute on zIIPs. Running the Acme Air benchmark on zCX, up to 98% of the zCX CPU consumption was measured to be zIIP eligible. (See note below.)

A good first assumption is that the new work running in the zCX environment will be 95% zIIP-eligible. However, your zCX environment may be more or less zIIP eligible depending on characteristics of the workload. Capacity planning should be based on the measured zIIP eligibility of your specific zCX applications. zCX can be deployed exclusively on standard processors if no zIIP processors are available. See "Exploiting zIIP and general purpose processors for zCX workloads" in the IBM z/OS Container Extensions Guide for more information.

Note: Results were extrapolated from internal IBM benchmarks performed in a controlled environment using a single z14 z/OS 2.4 LPAR with TCP/IP inbound workload queuing (IWQ) for inbound traffic and two zCX containers: one running Node.js and one running a MongoDB database. zIIP eligibility is based on the CPU consumption of the work running on the zCX address spaces and the associated work on the TCPIP and VTAM address spaces. Results may vary.

Q: Are licenses required for applications running inside z/OS Container Extensions?

A: Yes, any licenses that you would procure to run applications in a traditional Linux on IBM Z environment will also be required to run those same applications inside zCX. Licenses are the same as those used for traditional Linux on IBM Z applications. If you are using an application on both Linux on IBM Z and zCX environments, ensure you have enough licensed capacity available to run the application on all the cores on which it will be active.

Q: Is Processor Value Unit (PVU) Licensing effective for IBM applications running inside z/OS Container Extensions?

A: Yes, whatever PVU licensing is in effect for IBM software in the traditional Linux on IBM Z environment is also in effect for zCX. Both General Purpose and zIIP engines are counted as cores.

PVU licensing for Passport Advantage® Products

Q: Will subcapacity pricing for Linux on IBM Z IBM SW (Passport Advantage products) be supported in zCX?

A: Yes, sub-capacity pricing is supported through the IBM License Metric Tool.

For more information on IBM License Metric Tool enablement on zCX, refer to Using the IBM License Metric Tool for sub-capacity pricing.

Use of IBM License Metric Tool is now mandatory for sub-capacity pricing for the zCX environment. Manual reporting is no longer acceptable.

Q: What can run in z/OS Container Extensions?

A: Anything with s390x architecture (the IBM Z opcode set) in Docker hub can be run in zCX. The code is binary compatible between Linux on IBM Z and Container Extensions.

In addition to open source packages, there will likely be IBM and third-party software available. It is intended that clients can participate with their own Linux applications, which can easily be packaged in Docker format and deployed in the same as open source, IBM, and vendor packages.

Q: On which engine types can z/OS Container Extensions run?

A: z/OS Container Extensions address spaces are zIIP-eligible. Most zCX processing (including Docker containers deployed within zCX) can be dispatched on available zIIP processors. Some zCX processing will be dispatched on standard processors. This will generally be a much smaller percentage of processor cycles compared to what can execute on zIIPs. Running the Acme Air benchmark on zCX, up to 98% of the zCX CPU consumption was measured to be zIIP eligible. (See note.)

A good first assumption is that the new work running in the zCX environment will be 95% zIIP-eligible. However, your zCX environment may be more or less zIIP eligible depending on characteristics of the workload. Capacity planning should be based on the measured zIIP eligibility of your specific zCX applications. zCX can be deployed exclusively on standard processors if no zIIP processors are available. See "Exploiting zIIP and general purpose processors for zCX workloads" in the IBM z/OS Container Extensions Guide for more information.

Note: Results were extrapolated from internal IBM benchmarks performed in a controlled environment using a single z14 z/OS 2.4 LPAR with TCP/IP inbound workload queuing (IWQ) for inbound traffic and two zCX containers: one running Node.js and one running a MongoDB database. zIIP eligibility is based on the CPU consumption of the work running on the zCX address spaces and the associated work on the TCPIP and VTAM address spaces. Results may vary.