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: receiving an instruction to upgrade an older version of a distributed software program installed on each of a plurality of nodes forming the cluster; installing and activating a newer version of software on a subset of the plurality of nodes, the subset having fewer nodes than the entire cluster; receiving an instruction to forcibly upgrade the cluster; and upgrading the cluster so that the subset of nodes operate with the newer version of software, wherein each node remains a member of the cluster during the upgrade.