Appendix B

Improving filer performance

About this appendix

This appendix describes configuration procedures that might improve your filer's performance.

Balance NFS traffic on network interfaces

Attach multiple interfaces on the filer to the same physical network to balance network traffic among different interfaces. For example, if two Ethernet interfaces on the filer named toaster are attached to the same network where four NFS clients reside, specify in the /etc/fstab file on client1 and client2 that these clients mount from toaster-0:/home. Specify in the /etc/fstab file on client3 and client4 that these clients mount from toaster-1:/home. This scheme can balance the traffic among interfaces if all clients generate about the same amount of traffic.

The filer always responds to an NFS request by sending its reply on the interface on which the request was received.

Correct duplex mismatches on a 10Base-T or 100Base-T Ethernet networks

On 10Base-T or 100Base-T Ethernet networks, the speed and duplex settings for the interfaces at both ends of a link must match exactly. Use the ifconfig interface command to check the duplex setting of the filer's interface. If the setting is set to autonegotiate, the ifconfig command displays a setting that begins with auto (for example, auto-100tx-fd-up). Otherwise, the ifconfig command displays the setting (for example, 100tx-fd-up).

Note
If one end of the link is set to autonegotiate, the other end must also be set to autonegotiate; otherwise, a mismatch might occur. You can determine the negotiated setting with the ifstat command.

Make optimal use of Slot 8

This method of improving filer performance applies to F700 series filers only. The fastest available PCI slot in an F700 series filer that is not clustered is Slot 8. If your filer uses a 64-bit network interface card, put it in Slot 8 to take advantage of the speed. If the filer does not use a 64-bit network interface card, put the main FC-AL adapter in this slot.

Upgrade to a faster network interface

You can increase filer performance by upgrading to a faster network interface. The following lists network interfaces from the fastest to the slowest:

Gigabit Ethernet interfaces
ATM OC-12 interfaces
Gigabit Ethernet interface
ATM OC-3 interface
Fast Ethernet 100Base-T interface
F700 series onboard 100Base-T interfaces
Znyx 100Base-T and FDDI interfaces
10Base-T interface

Determine when to use UDP or TCP transport

The following are guidelines to determine when you should use the UDP transport or the TCP transport to improve filer performance:

Use the TCP transport over a WAN network.
Use the UDP transport over a LAN network.
Use the TCP transport if you are using the UDP transport and you experience packet loss, especially during periods of heavy write traffic.

You can specify the transport using the options nfs.tcp.enable command.

Adjust flow control for Gigabit Ethernet II on F700 series filers

If you are using the Gigabit Ethernet II interface on an F700 series filer that is connected to a switch, you can adjust the flow control to improve maximum transmit performance. The default flow control setting full should be changed to send or none. Most switches rarely send flow control frames, so disabling receive should not cause problems. This does not apply to other Gigabit Ethernet interfaces or other platforms.

Note
Do not perform this tuning when the interface is connected back-to-back with another host machine. In this situation, the flow control setting should be set to full on both sides to avoid overruns and poor performance.