While the documentation states 50GB : https://docs.redhat.com/en/documentation/openshift_container_platform/4.20/html-single/installing_a_two_node_openshift_cluster/index#installation-two-node-fencing-minimum-resource-requirements_installing-two-node-fencing

After trying to install using the Agent Based Installer for a 2 nodes with Arbiter cluster, it fails, claiming it requires 100GB to install the Arbiter.

Then, I checked the repository and it looks like the minimum requirement is set to 100GB.

https://github.com/openshift/assisted-service/blob/master/data/default_hw_requirements.json#L14

    

Always
    

    1. Set up environment to install 2 nodes with arbiter installation on bare-metal.
    2. Create the arbiter node with 50 GB disk size
    3. Try to use the agent-based installer and it will fail.
    

Installation fails
    

The arbiter node should be installed with 50GB disk.
    

Created KCS for this: https://access.redhat.com/solutions/7139003