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Chapter 10. Adjusting Network Settings
# sysctl -w net.core.wmem_max=262144
To make the change permanent, add the following lines to the /etc/sysctl.conf file, which is used
during the boot process:
net.core.rmem_default=262144
net.core.wmem_default=262144
net.core.rmem_max=262144
net.core.wmem_max=262144
To improve fail over performance in a RAC cluster, consider changing the following IP kernel
parameters as well:
net.ipv4.tcp_keepalive_time
net.ipv4.tcp_keepalive_intvl
net.ipv4.tcp_retries2
net.ipv4.tcp_syn_retries
Changing these settings may be highly dependent on your system, network, and other applications.
For suggestions, see Metalink Note:249213.1 and Note:265194.1.
On Red Hat Enterprise Linux systems the default range of IP port numbers that are allowed for TCP
and UDP traffic on the server is too low for 9i and 10g systems. Oracle recommends the following port
range:
# sysctl -w net.ipv4.ip_local_port_range="1024 65000"
To make the change permanent, add the following line to the /etc/sysctl.conf file, which is used during
the boot process:
net.ipv4.ip_local_port_range=1024 65000
The first number is the first local port allowed for TCP and UDP traffic, and the second number is the
last port number.
10.3. Flow Control for e1000 Network Interface Cards
The e1000 network interface card family do not have flow control enabled in the 2.6 kernel on Red Hat
Enterprise Linux 4 and 5. If you have heavy traffic, then the RAC interconnects may lose blocks, see
1
Flow control
Metalink Bug:5058952. For more information on flow control, see Wikipedia
.
To enable Receive flow control for e1000 network interface cards, add the following line to the /etc/
modprobe.conf file:
options e1000 FlowControl=1
The e1000 module needs to be reloaded for the change to take effect. Once the module is loaded with
flow control, you should see e1000 flow control module messages in /var/log/messages.
1
http://en.wikipedia.org/wiki/Flow_control
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