Reading Time: 2 minutes The Reduced Downtime Upgrade (RDU) is a new mechanism introduced in vSphere 8.x for upgrade/update the self-managed vCenter Servers with a minimal downtime (lesser compared to normal upgrade/update procedure). What is the Self-managed vCenter Server? It’s a vCenter Server that manages its own ESXi host and its own virtual machine. More information are available in KB 92659 (vCenter Server upgrades with the reduced downtime).
