Configuration of kernel parameters

Configuring Kernel Parameters

If the value of any kernel parameter is different from the recommended value, then complete the following procedure:

Using any text editor, create or edit the /etc/sysctl.conf file, and add or edit lines similar to the following:

Note:

Include lines only for the kernel parameter values that you want to change. For the semaphore parameters (kernel.sem), you must specify all four values. However, if any of the current values are larger than the recommended value, then specify the larger value.

fs.file-max = 512 * PROCESSES
kernel.shmall = 2097152
kernel.shmmax = 2147483648
kernel.shmmni = 4096
kernel.sem = 250 32000 100 128
net.ipv4.ip_local_port_range = 1024 65000
net.core.rmem_default = 4194304
net.core.rmem_max = 4194304
net.core.wmem_default = 262144
net.core.wmem_max = 262144

Note: If the current value for any parameter is higher than the value listed in this table, then do not change the value of that parameter.

By specifying the values in the /etc/sysctl.conf file, they persist when you restart the system.

Enter the following command to change the current values of the kernel parameters:

# /sbin/sysctl -p

Setting Shell Limits for the oracle User

To improve the performance of the software on Linux systems, you must increase the following shell limits for the oracle user:

Shell Limit Item in limits.conf Hard Limit

Maximum number of open file descriptors nofile 65536
Maximum number of processes available to a single user nproc 16384

To increase the shell limits:

Add the following lines to the /etc/security/limits.conf file:

oracle soft nproc 2047
oracle hard nproc 16384
oracle soft nofile 1024
oracle hard nofile 65536

Add or edit the following line in the /etc/pam.d/login file, if it does not already exist:

session required /lib/security/pam_limits.so
session required pam_limits.so

Note:

For 64-bit platforms, the following entry is not required in the /etc/pam.d/login file:

session required /lib/security/pam_limits.so

Depending on the oracle user's default shell, make the following changes to the default shell start-up file:

For the Bourne, Bash, or Korn shell, add the following lines to the /etc/profile file (or the file on SUSE systems)/etc/profile.local:

if [ $USER = "oracle" ]; then
if [ $SHELL = "/bin/ksh" ]; then
ulimit -p 16384
ulimit -n 65536
else
ulimit -u 16384 -n 65536
fi
fi

For the C shell (csh or tcsh), add the following lines to the /etc/csh.login file (or the file on SUSE systems)/etc/csh.login.local:

if ( $USER == "oracle" ) then
limit maxproc 16384
limit descriptors 65536
endif