Node and disk management
At a minimum, you must deploy four nodes in a cluster and can scale up to a maximum of sixteen nodes. All the nodes must have the same hardware and the same software version.
A cluster with up to five nodes provides resiliency of one node and a disk. The cluster can tolerate a loss of one node and a disk and continue to perform NetBackup jobs. A cluster with six or more nodes provides resiliency of two nodes, or two SSDs, or four HDDs. If the loss of cluster nodes is more than the supported resiliency, either due to node failure or nodes are stopped or shut down, the cluster goes in an inconsistent state. If a cluster is in an inconsistent state, check the NetBackup Flex Scale Release Notes to see if a related issue and the resolution is mentioned; else call Veritas Technical Support for assistance with resolving the inconsistent cluster state.
Replace a faulted node or disk in the cluster to recover from a node or a disk failure. Add a new node to the cluster to increase the usable cluster storage and compute resources. When you add a node or replace a faulted node, the NetBackup operations continue to run on the cluster nodes.