1. A method for facilitating an upgrade of a cluster of servers in the presence of one or more inaccessible nodes in the cluster, comprising: upgrading a version of a distributed software on each of a plurality of nodes in the cluster to a newer version; detecting that one or more nodes of the cluster are inaccessible; continuing to upgrade nodes in the cluster other than the inaccessible nodes, wherein the upgrading involves installing and activating the newer version of the distributed software on the nodes being upgraded; upgrading an acting version of the cluster to the newer version of the distributed software; activating the newer version of the distributed software on a previously inaccessible node; and joining the previously inaccessible node to the cluster so that the previously inaccessible node becomes an active member of the cluster, wherein each node of the cluster including the previously inaccessible node operates according to the upgraded acting version of the cluster corresponding to the newer version of the distributed software.