Oracle for Beginner: Knowing your Linux Kernel Parameter for Oracle

If you want to know about how to install Oracle 10g on your Linux, there are some interesting articles that may be can help you to inform step by step installation. Here are some of those:

• Oracle-Base (this site is a famous one)
• Dizwell Informatics (installing Oracle10g on Ubuntu)
  
• OTN Oracle-on-Linux.

From those guides, before installation is started, there are some kernel parameters that have to be setup in /etc/sysctl.conf files. Here are from Oracle-Base:

kernel.shmall = 2097152
kernel.shmmax = 2147483648
kernel.shmmni = 4096
# semaphores: semmsl, semmns, semopm, semmni
kernel.sem = 250 32000 100 128
fs.file-max = 65536

kernel.shm* are parameters that is used to configure shared memory in Linux. Shared memory is a system resource that is used for interprocess communication. With this technique, two or more processes share a single chunk of memory to communicate between them. Shared memory is allocated in segments.

• shmall : define the maximum amount of shared memory that may be in use at any time on the system.
• shmmax : define the maximum size of each shared memory segment (max. value is 4GB).
• shmmni : define the maximum number of shared memory segments on the system.
  

Semaphore is an important mechanism for controlling access to resources. Oracle instance use semaphore to control access to shared memory. Here is the kernel parameter which is used to configure the semaphore:

# semaphores: semmsl, semmns, semopm, semmni
kernel.sem = 250 32000 100 128

• semmsl: maximum number of semaphores per set.
• semmns : total number of semaphores in the system.
• semopm : maximum number of operations per semop call.
• semmni : maximum number of semaphore sets.
  

fs.file-max is a file handle parameter that determines the maximum number of files that each process can open. Default value is 8192 and the maximum value is 65536.

For more information, please refer to puschtz and dba-oracle.com .