Chapter 2. Preparing to install with the Assisted Installer Before installing a cluster, you must ensure the cluster nodes and network meet the requirements. 2.1. Prerequisites 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. If you use a firewall, you must configure it so that Assisted Installer can access the resources it requires to function. 2.2. Assisted Installer prerequisites The Assisted Installer validates the following prerequisites to ensure successful installation. 2.2.1. CPU Architectures The Assisted installer is supported on the following CPU architectures: x86_64 arm64 ppc64le s390x 2.2.2. Hardware For Single Node Openshift (SNO), the Assisted Installer requires one host with at least 8 CPU cores, 16 GiB RAM, and 100 GB disk size. For multi-node clusters, control plane hosts must have at least the following resources: 4 CPU cores 16.00 GiB RAM 100 GB storage 10ms write speed or less for etcd wal_fsync_duration_seconds For multi-node clusters, worker hosts must have at least the following resources: 2 CPU cores 8.00 GiB RAM 100 GB storage For hosts of type vMware , set clusterSet disk.enableUUID to true , even when the platform is not vSphere. 2.2.3. Networking The network must meet the following requirements: A DHCP server unless using static IP addressing. A base domain name. You must ensure that the following requirements are met: There is no wildcard, such as *.<cluster_name>.<base_domain> , or the installation will not proceed. A DNS A/AAAA record for api.<cluster_name>.<base_domain> . A DNS A/AAAA record with a wildcard for *.apps.<cluster_name>.<base_domain> . Port 6443 is open for the API URL if you intend to allow users outside the firewall to access the cluster via the oc CLI tool. Port 443 is open for the console if you intend to allow users outside the firewall to access the console. A DNS A/AAAA record for each node in the cluster when using User Managed Networking, or the installation will not proceed. DNS A/AAAA records are required for each node in the cluster when using Cluster Managed Networking after installation is complete in order to connect to the cluster, but installation can proceed without the A/AAAA records when using Cluster Managed Networking. A DNS PTR record for each node in the cluster if you want to boot with the preset hostname when using static IP addressing. Otherwise, the Assisted Installer has an automatic node renaming feature when using static IP addressing that will rename the nodes to their network interface MAC address. Important DNS A/AAAA record settings at top-level domain registrars can take significant time to update. Ensure the A/AAAA record DNS settings are working before installation to prevent installation delays. The OpenShift Container Platform cluster's network must also meet the following requirements: Connectivity between all cluster nodes Connectivity for each node to the internet Access to an NTP server for time synchronization between the cluster nodes 2.2.4. Preflight validations The Assisted Installer ensures the cluster meets the prerequisites before installation, because it eliminates complex post-installation troubleshooting, thereby saving significant amounts of time and effort. Before installing software on the nodes, the Assisted Installer conducts the following validations: Ensures network connectivity Ensures sufficient network bandwidth Ensures connectivity to the registry Ensures that any upstream DNS can resolve the required domain name Ensures time synchronization between cluster nodes Verifies that the cluster nodes meet the minimum hardware requirements Validates the installation configuration parameters If the Assisted Installer does not successfully validate the foregoing requirements, installation will not proceed.

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