HP ProLiant DL380G5-WSS 3.7.0 HP StorageWorks HP Scalable NAS File Serving Sof - Page 199
Adjust the NIC parameters, typically created when the OS is installed.
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• Disable Ethernet flow control. The TCP/IP protocol has its own flow-control mechanism and can better handle overrun conditions. (Check your NIC documentation to determine whether this feature can be disabled.) If you have made the NIC changes described above and suspect that your systems still have networking issues, make the following additional network changes: • TCP Segmentation Offload (TSO). The TCP protocol stack in the kernel must take a stream of data and convert it into IP datagrams for transmission over the network. The TSO feature offloads this action to the hardware in the NIC. Testing has shown that disabling this feature can improve network performance. (Check your NIC documentation to determine whether changing the value is supported.) • Depending on your network interface card, you may want to increase the size of the NIC transmit queue maintained by the driver for the interface. (Check the documentation for your NIC to determine whether changing the value is supported.) The adjustment may allow the network stack to continue queuing data to the interface after the internal hardware buffers are completely used. Be conservative when increasing the value. The recommended value is 5000. Adjust the NIC parameters To set the NIC parameters, you will need to add commands to the appropriate file for your operating system, as described below. The files are executed after the system is booted, specifically after all run-level scripts are completed. • On RHEL5 systems, add the commands to the /etc/rc.local file. This file is typically created when the OS is installed. • On SLES10 systems, add the commands to the /etc/after.local file. You may need to create this file. The commands to modify the parameters are as follows. To change the parameters in real time, execute the commands on the command line. • Disable Ethernet flow control: ethtool -A eth0 tx off rx off • Disable the TSO feature: ethtool -K eth0 tso off • Increase the size of the NIC transmit queue on a per-interface basis: # ip link set eth0 txqueuelen 3000 After adjusting the NIC values, it is a good idea to check the NIC statistics with the ethtool -S command. HP Scalable NAS File Serving Software administration guide 199