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Oracle Solaris Tunable Parameters Reference Manual     Oracle Solaris 10 8/11 Information Library
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1.  Overview of Oracle Solaris System Tuning

What's New in Oracle Solaris System Tuning?

Oracle Solaris System Tuning in the Solaris 10 Release

Default Stack Size

System V IPC Configuration

NFSv4 Parameters

New and Changed TCP/IP Parameters

IP Forwarding Changes

SPARC: Translation Storage Buffer (TSB) Parameters

SCTP Tunable Parameters

Tuning an Oracle Solaris System

Tuning Format of Tunable Parameters Descriptions

Tuning the Oracle Solaris Kernel

/etc/system File

Example--Setting a Parameter in /etc/system

Recovering From an Incorrect Value

kmdb Command

mdb Command

Example-Using mdb to Display Information

Special Oracle Solaris tune and var Structures

Viewing Oracle Solaris System Configuration Information

sysdef Command

kstat Utility

2.  Oracle Solaris Kernel Tunable Parameters

3.  NFS Tunable Parameters

4.  Internet Protocol Suite Tunable Parameters

5.  Network Cache and Accelerator Tunable Parameters

6.  System Facility Parameters

A.  Tunable Parameters Change History

B.  Revision History for This Manual


Tuning an Oracle Solaris System

The Oracle Solaris OS is a multi-threaded, scalable UNIX operating system that runs on SPARC and x86 processors. It is self-adjusting to system load and demands minimal tuning. In some cases, however, tuning is necessary. This book provides details about the officially supported kernel tuning options available for the Oracle Solaris OS.

The Solaris kernel is composed of a core portion, which is always loaded, and a number of loadable modules that are loaded as references are made to them. Many variables referred to in the kernel portion of this guide are in the core portion. However, a few variables are located in loadable modules.

A key consideration in system tuning is that setting system parameters (or system variables) is often the least effective action that can be done to improve performance. Changing the behavior of the application is generally the most effective tuning aid available. Adding more physical memory and balancing disk I/O patterns are also useful. In a few rare cases, changing one of the variables described in this guide will have a substantial effect on system performance.

Remember that one system's /etc/system settings might not be applicable, either wholly or in part, to another system's environment. Carefully consider the values in the file with respect to the environment in which they will be applied. Make sure that you understand the behavior of a system before attempting to apply changes to the system variables that are described here.

We recommend that you start with an empty /etc/system file when moving to a new Oracle Solaris release. As a first step, add only those tunables that are required by in-house or third-party applications. Any tunables that involve System V IPC (semaphores, shared memory, and message queues) have been modified in the Oracle Solaris 10 release and should be changed in your environment. For more information, see System V IPC Configuration. After baseline testing has been established, evaluate system performance to determine if additional tunable settings are required.


Caution - The tunable parameters described in this book can and do change from Oracle Solaris release to Oracle Solaris release. Publication of these tunable parameters does not preclude changes to the tunable parameters and their descriptions without notice.