All SMB users are reporting that their network share performance is slow on a new NetApp FAS500f HA pair. You determine that the users have converged network adapters (CNAs) with flow control enabled and no option to disable.
In this scenario, which two flow control settings are recommended on the NetApp ONTAP physical ports? (Choose two.)
In a NetApp ONTAP environment, it is recommended to disable flow control on both data network ports and cluster network ports. This is because enabling flow control can lead to increased latency and performance degradation, especially with protocols sensitive to delays, such as SMB. Disabling flow control ensures that unnecessary pauses in data transmission are avoided, maintaining optimal performance and preventing issues related to the cluster heartbeat mechanism.
Consensus
Clustered Data ONTAP / ONTAP 9 Flow control recommendations: Disable flow control on cluster network ports in the Data ONTAP cluster. Flowcontrol on the remaining network ports (the ports that provide data, management, and intercluster connectivity) should be configured to match the settings within the rest of your environment.
B,C is correct. https://kb.netapp.com/Advice_and_Troubleshooting/Data_Storage_Software/ONTAP_OS/What_are_the_flow_control_best_practices_for_Ethernet%3F#Clustered_Data_ONTAP_.2F_ONTAP_9_Flow_control_recommendations:
AC are right ones as in question it's clearly mentioned that user cannot disable flow control on CNA. As NetApp's current recommendation for flow control is to be disabled on the cluster network, but makes no recommendation for the data network. The only option is to enable flow control on data NW.
BC https://kb.netapp.com/Advice_and_Troubleshooting/Data_Storage_Software/ONTAP_OS/What_are_the_flow_control_best_practices_for_Ethernet%3F
B and C is Correct
BC: Historically (7-Mode/clustered Data ONTAP), NetApp had recommended that flow control be disabled on all network ports within a NetApp Data ONTAP cluster. This approach is no longer the case. Guidance in this area has since changed, the new recommended best practice is as follows: Disable flow control on cluster network ports in the Data ONTAP cluster. Flowcontrol on the remaining network ports (the ports that provide data, management, and intercluster connectivity) should be configured to match the settings within the rest of your environment.
Flow control is a mechanism that allows a network device to pause the transmission of data from another device when its receive buffer is full. Flow control can be useful to prevent packet loss and congestion in some scenarios, but it can also cause performance degradation and latency in others1 According to the NetApp best practices, flow control should be disabled on cluster network ports in the ONTAP cluster. This is because flow control can interfere with the cluster heartbeat mechanism and cause unnecessary failovers or false alarms Flow control should also be disabled on data network ports in the ONTAP cluster, especially when using SMB protocol. This is because SMB is sensitive to latency and flow control can introduce delays and jitter in the data transmission.
Disable flow control end-to-end on cluster network ports and is disabled by default