You are planning a single-site Nimble solution with iSCSI connectivity.

When designing an Intelligent Resilient Framework (IRF) stack for a Nimble storage solution using HPE FlexFabric 5900CP switches with iSCSI connectivity, the IRF stack typically supports up to two switches for optimal performance and redundancy. This limitation ensures that the iSCSI traffic is managed effectively without overcomplicating the network topology, which could potentially introduce latency or complexity in managing the stack.

Utilizing more than two switches in an IRF stack when connecting to storage could result in diminished returns in performance or increased management overhead, which is why HPE typically recommends limiting the IRF stack to two switches in such configurations.

For further details, refer to:

HPE Nimble Storage Overview

HPE FlexFabric Switches