Nondisruptive upgrades (NDUs) allow a cluster administrator to upgrade the storage operating system while their end users continue to access data without error or interruption. Updating the operating system on a cluster is a simple matter of a rolling upgrade. During this process, one node at a time is upgraded to the new code, and the active NFS and SMB3 clients attached to it are automatically migrated to other nodes in the cluster. Partial upgrade is also permitted, whereby a subset of cluster nodes can be upgraded. The subset of nodes may also be grown during the upgrade. Beginning with OneFS 8.2, an upgrade can be paused and resumed, allowing customers to span upgrades over multiple smaller maintenance windows.
