US Patent 11412040 Using maintenance mode to upgrade a distributed system

The present disclosure relates to using maintenance mode to upgrade a distributed system. One method includes determining that a first host of a cluster of a software-defined datacenter (SDDC) is to be upgraded as a part of a rolling upgrade of the hosts of the cluster, wherein the first host is executing a process instance of a cluster store, demoting the process instance to a proxy, creating a replica of the process instance using a different proxy on a second host of the cluster, instructing the first host to enter a maintenance mode, upgrading the first host, and instructing the first host to leave the maintenance mode.