Installation guide

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=4194304
net.core.wmem_max=262144
Minimum, default and maximum values of TCP socket send and receive buffers should correspond to the set-
tings above:
net.ipv4.tcp_rmem=4096 262144 4194304
net.ipv4.tcp_wmem=4096 262144 262144
To improve failover performance in a RAC cluster, consider changing the following IP kernel parameters as
well:
net.ipv4.tcp_keepalive_time=30
net.ipv4.tcp_keepalive_intvl=60
net.ipv4.tcp_keepalive_probes=9
net.ipv4.tcp_retries2=3
net.ipv4.tcp_syn_retries=2
Changing these settings may be highly dependent on your system, network, and other applications. For sugges-
tions, see Metalink Note:249213.1.
On Red Hat Enterprise Linux systems, the default range of IP port numbers that are allowed for TCP and UDP
traffic is too low for Oracle database servers. 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.
Flow Control on NICs and Network Switches
Verify that NICs and network switches are using flow control. If you have heavy traffic, then the RAC intercon-
nects may lose blocks, see Metalink Bug:5058952.
To verify flow control settings on the NIC use ethtool:
# ethtool -k eth0
Make sure you have flow control enabled in both direction: for transmit (Tx) and receive (Rx). Some switches
have flow control enabled by default for Rx only. Ask you network administrator to fix switch settings, if neces-
sary.
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