Checking Kernel Parameters

To see all kernel parameters, execute:

su - root
sysctl -a

For Oracle10g, the following kernel parameters have to be set to values greater than or equal to the recommended values which can be changed in the proc filesystem:

shmmax  = 2147483648     (To verify, execute: cat /proc/sys/kernel/shmmax)
shmmni  = 4096           (To verify, execute: cat /proc/sys/kernel/shmmni)
shmall  = 2097152        (To verify, execute: cat /proc/sys/kernel/shmall)   (for 10g R1)
shmmin  = 1              (To verify, execute: ipcs -lm |grep "min seg size")
shmseg  = 10             (It's hardcoded in the kernel - the default is much higher)

semmsl  = 250            (To verify, execute: cat /proc/sys/kernel/sem | awk '{print $1}')
semmns  = 32000          (To verify, execute: cat /proc/sys/kernel/sem | awk '{print $2}')
semopm  = 100            (To verify, execute: cat /proc/sys/kernel/sem | awk '{print $3}')
semmni  = 128            (To verify, execute: cat /proc/sys/kernel/sem | awk '{print $4}')

file-max = 65536         (To verify, execute: cat /proc/sys/fs/file-max)

ip_local_port_range = 1024 65000
                        (To verify, execute: cat /proc/sys/net/ipv4/ip_local_port_range)

NOTE: Do not change the value of any kernel parameter on a system where it is already higher than listed as minimum requirement.

On RHEL AS 4 x86, RHEL AS 3 U5 x86, RHEL AS 3 U5 x86_64, RHEL AS 2.1, RH9, FC1, FC3, and FC4 I had to increase the kernel parameters shmmax, semopm, and filemax to meet the minimum requirement. On RHEL AS 4 x86_64 I had to increase shmmax and semopm.

Oracle also recommends to set the local port range ip_local_port_range for outgoing messages to "1024 65000" which is needed for high-usage systems. This kernel parameter defines the local port range for TCP and UDP traffic to choose from.

I added the following lines to the /etc/sysctl.conf file which is used during the boot process:

kernel.shmmax=2147483648
kernel.sem=250 32000 100 128
fs.file-max=65536
net.ipv4.ip_local_port_range=1024 65000

Adding these lines to the /etc/sysctl.conf file will cause the system to change these kernel parameters after each boot using the /etc/rc.d/rc.sysinit script which is invoked by /etc/inittab. But in order that these new added lines or settings in /etc/sysctl.conf become effective immediately, execute the following command:

su - root
sysctl -p

Starting with 10g R2 some network settings must be adjusted as well which is checked by OUI. For more information on setting these parameters
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