16 Configure Kernel Parameter and number of open file descriptor

maximum number of open file descriptors: nofiles

Global setting can be found via /proc/sys/fs/file-max

Change it can be done via /etc/security/limits.conf

# soft limit

ulimit -Sn

# Hard Limit

ulimit -Hn

Maximum number of processes available to a single user: nproc

ulimit -Su

ulimit -Hu

 

Kernel Parameter

Check current value:

sysctl -a

Below is the Oracle recommendation kernel parameters.

semmsl semmns semopm semmni	250 32000 100 128	/proc/sys/kernel/sem
shmmni	4096	/proc/sys/kernel/shmmni
shmmax	Recommended: More than half the physical memory	/proc/sys/kernel/shmmax
file-max	6815744	/proc/sys/fs/file-max
ip_local_port_range	Minimum: 9000 Maximum: 65500	/proc/sys/net/ipv4/ip_local_port_range
rmem_default	262144	/proc/sys/net/core/rmem_default
rmem_max	4194304	/proc/sys/net/core/rmem_max
wmem_default	262144	/proc/sys/net/core/wmem_default
wmem_max	1048576	/proc/sys/net/core/wmem_max
aio-max-nr	1048576	/proc/sys/fs/aio-max-nr

 

To make the changes, we can update /etc/sysctl.conf

Once the file is being update, we can run below command to make it effective,

/sbin/sysctl -p

 

We  can use ipcs –lm to check the

 

 

 

Reference

• http://gerardnico.com/wiki/linux/limits.conf
• http://www.oracle-base.com/articles/11g/oracle-db-11gr2-installation-on-oracle-linux-6.php