Before file-level resources are shared from a PowerStore T/Q model system, NAS server interfaces must be configured using either the default system bond on the first two ports of the 4-port card or a user-defined Link Aggregation Group. User-defined link aggregation groups are available for file storage since PowerStoreOS 3.0.  PowerStoreOS 4.0 and later expanded support for iSCSI and replication purposes. For more information about link aggregation, see the section Link Aggregation Control Protocol (LACP).

An administrator can create a NAS server that holds the configuration information for SMB, NFS, FTP, or SFTP access to the file systems. New NAS servers are automatically assigned on a round-robin basis across the available nodes. The preferred node acts as a marker to indicate the node on which the NAS server should be running, based on this algorithm. After it is provisioned, the preferred node for a NAS server never changes. The current node indicates the node on which the NAS server is running. Changing the current node moves the NAS server to a different node, which can be used for loading balancing purposes. When you move a NAS server to a new node, all file systems on the NAS server move along with it.

The following figure shows the current and preferred node columns in PowerStore Manager.

Figure 38.    Current Node and Preferred Node

During a PowerStore node failure, the NAS servers automatically fail over to the surviving node. This process generally completes within 30 seconds to avoid host timeouts. After the failed node is recovered, a manual process is required to fail back the NAS servers and return to a balanced configuration.

NAS servers are automatically moved to the peer node and back during the upgrade process. After the upgrade is completed, the NAS servers return to the node that they were assigned to at the beginning of the upgrade. For more information about NAS Servers, see the document PowerStore: File Capabilities.