Performance Tuning - Dell SC Series Configuration Manual

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Performance tuning

In testing of the VDX 6740 switch using asymmetric flow control (TX off, RX on), the default buffer
allocation of 280KB per port per queue did not yield optimum performance, and significant TCP
retransmits were observed.
With NOS version 5.0.1, system performance can be optimized by increasing TX and RX buffers (per port,
per queue). Optimal performance can be achieved when using a setting of 2MB for receive queue and
2MB for transmit queue per port.
The following instructions show how to configure the receive and transmit buffers.
sw0# configure
Entering configuration mode terminal
sw0(config)# rbridge-id 1
sw0(config-rbridge-id-1)# qos tx-queue limit 2000
sw0(config-rbridge-id-1)# qos rcv-queue limit 2000
sw0(config-rbridge-id-1)# exit
sw0(config)#
Note: Repeat the commands to configure the buffer on the second switch.
9 SCG2013 | Brocade VDX 6740 Switch Configuration Guide for Dell SC Series SANs