PowerStoreOS 3.5 adds Fail-Safe Networking (FSN) support for file interfaces. FSN is a high-availability feature that enables configuring ports in a primary/backup configuration. Under normal circumstances, the primary ports are designated as active and are used to service IO. If all primary ports of an FSN go offline, the backup ports automatically become active and continue to service IO. This enables redundancy in case of port, cable, or switch failure. When the primary ports are restored, the system automatically makes the primary ports active again.
FSN can be leveraged to increase resiliency in file networks, especially when Multi-Chassis Link Aggregation (MC-LAG) is not configured on the top-of-rack switches. MC-LAG enables the ability to create link aggregations across multiple switches. Without MC-LAG, link aggregations are limited to a single physical switch. If that switch goes offline, access to the NAS servers on that node becomes unavailable. Configuring FSN across multiple physical switches enables data access to continue even if a switch goes offline.
An FSN can consist of individual ports, Link Aggregations, or a combination of both. When used in conjunction with LA, multiple ports can be used as part of the active or backup part of the FSN. Leveraging both FSN and LA together provides high availability and load balancing. If the primary side of the FSN uses a LA, all ports of the LA must go down for the backup side to become active. Note that you cannot put the System Bond into an FSN.
An FSN can be created using a different configuration on the primary compared to the backup side, if desired. Members of an FSN can have different speed/duplex settings but must have the same MTU. Ports from different IO modules can be used in the FSN. FSNs created with more ports on one side compared to the other are also allowed. Note that having a mismatched configuration may have performance implications in failure scenarios.