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One physical core (IFL) provides two logical cores (threads) when SMT-2 is enabled. The hypervisor can provide two or more vCPUs.
In OpenShift Container Platform version 4.11, you can install a cluster on IBM Z or LinuxONE infrastructure that you provision.
While this document refers only to IBM Z, all information in it also applies to LinuxONE. |
Additional considerations exist for non-bare metal platforms. Review the information in the guidelines for deploying OpenShift Container Platform on non-tested platforms before you install an OpenShift Container Platform cluster. |
You reviewed details about the OpenShift Container Platform installation and update processes.
You read the documentation on selecting a cluster installation method and preparing it for users.
Before you begin the installation process, you must clean the installation directory. This ensures that the required installation files are created and updated during the installation process.
You provisioned persistent storage using OpenShift Data Foundation or other supported storage protocols for your cluster. To deploy a private image registry, you must set up persistent storage with ReadWriteMany
access.
If you use a firewall, you configured it to allow the sites that your cluster requires access to.
Be sure to also review this site list if you are configuring a proxy. |
In OpenShift Container Platform 4.11, you require access to the internet to install your cluster.
You must have internet access to:
Access OpenShift Cluster Manager Hybrid Cloud Console to download the installation program and perform subscription management. If the cluster has internet access and you do not disable Telemetry, that service automatically entitles your cluster.
Access Quay.io to obtain the packages that are required to install your cluster.
Obtain the packages that are required to perform cluster updates.
If your cluster cannot have direct internet access, you can perform a restricted network installation on some types of infrastructure that you provision. During that process, you download the required content and use it to populate a mirror registry with the installation packages. With some installation types, the environment that you install your cluster in will not require internet access. Before you update the cluster, you update the content of the mirror registry. |
For a cluster that contains user-provisioned infrastructure, you must deploy all of the required machines.
This section describes the requirements for deploying OpenShift Container Platform on user-provisioned infrastructure.
The smallest OpenShift Container Platform clusters require the following hosts:
Hosts | Description |
---|---|
One temporary bootstrap machine |
The cluster requires the bootstrap machine to deploy the OpenShift Container Platform cluster on the three control plane machines. You can remove the bootstrap machine after you install the cluster. |
Three control plane machines |
The control plane machines run the Kubernetes and OpenShift Container Platform services that form the control plane. |
At least two compute machines, which are also known as worker machines. |
The workloads requested by OpenShift Container Platform users run on the compute machines. |
To improve high availability of your cluster, distribute the control plane machines over different z/VM instances on at least two physical machines. |
The bootstrap, control plane, and compute machines must use Red Hat Enterprise Linux CoreOS (RHCOS) as the operating system.
Note that RHCOS is based on Red Hat Enterprise Linux (RHEL) 8 and inherits all of its hardware certifications and requirements. See Red Hat Enterprise Linux technology capabilities and limits.
Each cluster machine must meet the following minimum requirements:
Machine | Operating System | vCPU [1] | Virtual RAM | Storage | IOPS |
---|---|---|---|---|---|
Bootstrap |
RHCOS |
4 |
16 GB |
100 GB |
N/A |
Control plane |
RHCOS |
4 |
16 GB |
100 GB |
N/A |
Compute |
RHCOS |
2 |
8 GB |
100 GB |
N/A |
One physical core (IFL) provides two logical cores (threads) when SMT-2 is enabled. The hypervisor can provide two or more vCPUs.
If an instance type for your platform meets the minimum requirements for cluster machines, it is supported to use in OpenShift Container Platform.
You can install OpenShift Container Platform version 4.11 on the following IBM hardware:
IBM z16 (all models), IBM z15 (all models), IBM z14 (all models), IBM z13, and IBM z13s
LinuxONE, any version
The equivalent of six Integrated Facilities for Linux (IFL), which are SMT2 enabled, for each cluster.
At least one network connection to both connect to the LoadBalancer
service and to serve data for traffic outside the cluster.
You can use dedicated or shared IFLs to assign sufficient compute resources. Resource sharing is one of the key strengths of IBM Z. However, you must adjust capacity correctly on each hypervisor layer and ensure sufficient resources for every OpenShift Container Platform cluster. |
Since the overall performance of the cluster can be impacted, the LPARs that are used to setup the OpenShift Container Platform clusters must provide sufficient compute capacity. In this context, LPAR weight management, entitlements, and CPU shares on the hypervisor level play an important role. |
One instance of z/VM 7.1 or later
On your z/VM instance, set up:
Three guest virtual machines for OpenShift Container Platform control plane machines
Two guest virtual machines for OpenShift Container Platform compute machines
One guest virtual machine for the temporary OpenShift Container Platform bootstrap machine
To install on IBM Z under z/VM, you require a single z/VM virtual NIC in layer 2 mode. You also need:
A direct-attached OSA or RoCE network adapter
A z/VM VSwitch set up. For a preferred setup, use OSA link aggregation.
FICON attached disk storage (DASDs). These can be z/VM minidisks, fullpack minidisks, or dedicated DASDs, all of which must be formatted as CDL, which is the default. To reach the minimum required DASD size for Red Hat Enterprise Linux CoreOS (RHCOS) installations, you need extended address volumes (EAV). If available, use HyperPAV to ensure optimal performance.
FCP attached disk storage
16 GB for OpenShift Container Platform control plane machines
8 GB for OpenShift Container Platform compute machines
16 GB for the temporary OpenShift Container Platform bootstrap machine
3 LPARS that each have the equivalent of 6 IFLs, which are SMT2 enabled, for each cluster.
Two network connections to connect to both connect to the LoadBalancer
service and to serve data for traffic outside the cluster.
HiperSockets, which are attached to a node either directly as a device or by bridging with one z/VM VSWITCH to be transparent to the z/VM guest. To directly connect HiperSockets to a node, you must set up a gateway to the external network via a RHEL 8 guest to bridge to the HiperSockets network.
2 or 3 instances of z/VM 7.1 or later for high availability
On your z/VM instances, set up:
3 guest virtual machines for OpenShift Container Platform control plane machines, one per z/VM instance.
At least 6 guest virtual machines for OpenShift Container Platform compute machines, distributed across the z/VM instances.
1 guest virtual machine for the temporary OpenShift Container Platform bootstrap machine.
To ensure the availability of integral components in an overcommitted environment, increase the priority of the control plane by using the CP command SET SHARE
. Do the same for infrastructure nodes, if they exist. See SET SHARE in IBM Documentation.
To install on IBM Z under z/VM, you require a single z/VM virtual NIC in layer 2 mode. You also need:
A direct-attached OSA or RoCE network adapter
A z/VM VSwitch set up. For a preferred setup, use OSA link aggregation.
FICON attached disk storage (DASDs). These can be z/VM minidisks, fullpack minidisks, or dedicated DASDs, all of which must be formatted as CDL, which is the default. To reach the minimum required DASD size for Red Hat Enterprise Linux CoreOS (RHCOS) installations, you need extended address volumes (EAV). If available, use HyperPAV and High Performance FICON (zHPF) to ensure optimal performance.
FCP attached disk storage
16 GB for OpenShift Container Platform control plane machines
8 GB for OpenShift Container Platform compute machines
16 GB for the temporary OpenShift Container Platform bootstrap machine
Because your cluster has limited access to automatic machine management when you use infrastructure that you provision, you must provide a mechanism for approving cluster certificate signing requests (CSRs) after installation. The kube-controller-manager
only approves the kubelet client CSRs. The machine-approver
cannot guarantee the validity of a serving certificate that is requested by using kubelet credentials because it cannot confirm that the correct machine issued the request. You must determine and implement a method of verifying the validity of the kubelet serving certificate requests and approving them.
See Bridging a HiperSockets LAN with a z/VM Virtual Switch in IBM Documentation.
See Scaling HyperPAV alias devices on Linux guests on z/VM for performance optimization.
See Topics in LPAR performance for LPAR weight management and entitlements.
Recommended host practices for IBM Z & LinuxONE environments
All the Red Hat Enterprise Linux CoreOS (RHCOS) machines require networking to be configured in initramfs
during boot
to fetch their Ignition config files.
During the initial boot, the machines require an HTTP or HTTPS server to establish a network connection to download their Ignition config files.
The machines are configured with static IP addresses. No DHCP server is required. Ensure that the machines have persistent IP addresses and hostnames.
The Kubernetes API server must be able to resolve the node names of the cluster machines. If the API servers and worker nodes are in different zones, you can configure a default DNS search zone to allow the API server to resolve the node names. Another supported approach is to always refer to hosts by their fully-qualified domain names in both the node objects and all DNS requests.
You must configure the network connectivity between machines to allow OpenShift Container Platform cluster components to communicate. Each machine must be able to resolve the hostnames of all other machines in the cluster.
This section provides details about the ports that are required.