Its is important to know the most commonly used parameters in the pfile/spfile and their relationship with the kernel parameters to troubleshoot issues. The following table documents Unix and Linux kernel parameters that should be monitored and possibly increased after changes are made to the related init.ora parameter.
|Init.ora Parameter||Kernel Parameter|
|db_files (maxdatafiles)||nfile, maxfiles|
|processes||nproc, semmsl, semmns|
Common Kernel Parameter Definitions
The following Kernel Parameters tend to be generic across most Unix and Linux platforms. However, their names may be different on your platform.
- maxfiles – Soft file limit per process.
- maxuprc – Maximum number of simultaneous user processes per userid.
- nfile – Maximum number of simultaneously open files systemwide at any given time.
- nproc – Maximum number of processes that can exist simultaneously in the system.
- shmall – This parameter sets the total amount of shared memory pages that can be used system wide. Hence, shmall should always be at least ceil(shmmax/page_size).
- shmmax – The maximum size(in bytes) of a single shared memory segment.
- shmmin – The minimum size(in bytes) of a single shared memory segment.
- shmmni – The number of shared memory identifiers.
- shmseg – The maximum number of shared memory segments that can be attached by a process.
- semmns – The number of semaphores in the system.
- semmni – The number of semaphore set identifiers in the system; determines the number of semaphore sets that can be created at any one time.
- semmsl – The maximum number of sempahores that can be in one semaphore set. It should be same size as maximum number of Oracle processes.