Oracle Database Related Kernel Parameters

We add kernel parameters to /etc/sysctl.conf  manually or automatically with preinstall before Oracle installation started. Or we can modify these parameters after installation.

[root@rac1 fs]# cat /etc/sysctl.conf 

# oracle-database-server-12cR2-preinstall setting for fs.file-max is 6815744

fs.file-max = 6815744

# oracle-database-server-12cR2-preinstall setting for kernel.sem is '250 32000 100 128'

kernel.sem = 250 32000 100 256

# oracle-database-server-12cR2-preinstall setting for kernel.shmmni is 4096

kernel.shmmni = 4096

# oracle-database-server-12cR2-preinstall setting for kernel.shmall is 1073741824 on x86_64

kernel.shmall = 1073741824

# oracle-database-server-12cR2-preinstall setting for kernel.shmmax is 4398046511104 on x86_64

kernel.shmmax = 4398046511104

# oracle-database-server-12cR2-preinstall setting for kernel.panic_on_oops is 1 per Orabug 19212317

kernel.panic_on_oops = 1

# oracle-database-server-12cR2-preinstall setting for net.core.rmem_default is 262144

net.core.rmem_default = 262144

# oracle-database-server-12cR2-preinstall setting for net.core.rmem_max is 4194304

net.core.rmem_max = 4194304

# oracle-database-server-12cR2-preinstall setting for net.core.wmem_default is 262144

net.core.wmem_default = 262144

# oracle-database-server-12cR2-preinstall setting for net.core.wmem_max is 1048576

net.core.wmem_max = 1048576

# oracle-database-server-12cR2-preinstall setting for net.ipv4.conf.all.rp_filter is 2

net.ipv4.conf.all.rp_filter = 2

# oracle-database-server-12cR2-preinstall setting for net.ipv4.conf.default.rp_filter is 2

net.ipv4.conf.default.rp_filter = 2

# oracle-database-server-12cR2-preinstall setting for fs.aio-max-nr is 1048576

fs.aio-max-nr = 1048576

# oracle-database-server-12cR2-preinstall setting for net.ipv4.ip_local_port_range is 9000 65500

net.ipv4.ip_local_port_range = 9000 65500

Apply kernel parameters without server restart.

/sbin/sysctl -p

or

sysctl -p /etc/sysctl.conf

We can also check the status of parameters in Linux with following commands:

Example: Check aio status - current and max

[oracle@rac2 ~]$ sysctl -a | grep aio

fs.aio-max-nr = 1048576         --> This is the max number of allowable concurrent requests.

fs.aio-nr = 2088704                 --> This is the actual usage

[oracle@rac2 ~]$ cat /proc/sys/fs/aio-nr

2088704

As we can see from outputs actual usage is bigger than the max limit. So we have to optimize the kernel parameter. This is related to ASM and Oracle explained in following links:

https://blog.pythian.com/importance-oracle-database-related-kernel-parameters-aio-max-nr-bonus-track/

https://www.kernel.org/doc/Documentation/sysctl/fs.txt

 Error related to this parameter: ORA-27090 - Unable to Reserve Kernel Resources for Asynchronous Disk I/O