Tuning the Cluster Interconnect - Expert Oracle RAC Performance Diagnostics and Tuning - page 465

Table 14-3. Network-Related Kernel Parameters

Platform/Operating System Parameter

udp_recv_hiwat
udp_recv_hiwat

SUN/Solaris

rmem_default
rmem_max
wmem_default
wmem_max

Linux

udp_recvspace
udp_sendspace

True 64

tcp_xmit_hiwater_def
tcp_recv_hiwater_def

HP

Step 7
Monitoring the interconnect traffic using tools such as EM and IPTraf gives the indication that there are large packets
being transmitted, causing high latency of the interconnect. Figure 14-7 illustrates that the MTU size for the NIC is
at the default 1,500, and jumbo frames have not been configured. As noticed in the IPTraf output, most of them are
1,426-1,500+ sizes. This is probably because the Oracle block size is 8 K.

Figure 14-7. IPTraf output, MTU set at default