Abstract: A device, system, and method are directed towards upgrading software on a cluster. A cluster of nodes is divided into two partitions. The first partition is brought offline, and the software on each of its nodes is updated. The nodes are partially initialized and form an offline cluster, leaving uninitialized subsystems that share external resources or external communication. The second partition is brought offline. The nodes of the first partition complete their initialization and the first partition cluster is brought online. The nodes of the second partition are updated and join the first partition cluster. Quorum mechanisms are adjusted to allow each partition to operate as a cluster. The system thereby updates each node of the cluster with minimal time offline and without requiring software of different versions to intercommunicate.