Oracle Solaris Tunable Parameters Reference Manual

Tuning Format of Tunable Parameters Descriptions

The format for the description of each tunable parameter is as follows:

Parameter Name

Is the exact name that is typed in the /etc/system file, or found in the /etc/default/facility file.

Most parameters names are of the form parameter where the parameter name does not contain a colon (:). These names refer to variables in the core portion of the kernel. If the name does contain a colon, the characters to the left of the colon reference the name of a loadable module. The name of the parameter within the module consists of the characters to the right of the colon. For example:


Briefly describes what the parameter does or controls.

Data Type

Indicates the signed or unsigned short integer or long integer with the following distinctions:

  • On a system that runs a 32-bit kernel, a long integer is the same size as an integer.

  • On a system that runs a 64-bit kernel, a long integer is twice the width in bits as an integer. For example, an unsigned integer = 32 bits, an unsigned long integer = 64 bits.


(Optional) Describes the unit type.


What the system uses as the default value.


Specifies the possible range allowed by system validation or the bounds of the data type.

  • MAXINT – A shorthand description for the maximum value of a signed integer (2,147,483,647)

  • MAXUINT – A shorthand description for the maximum value of an unsigned integer (4,294,967,295)


Yes, if the parameter can be changed on a running system with the mdb or kmdb debugger. No, if the parameter is a boot time initialization only.


Checks that the system applies to the value of the variable either as specified in the /etc/system file or the default value, as well as when the validation is applied.


(Optional) Provides unstated constraints that might exist on the parameter, especially in relation to other parameters.

When to Change

Explains why someone might want to change this value. Includes error messages or return codes.

Zone Configuration

Identifies whether the parameter can be set in a exclusive-IP zone or must be set in the global zone. None of the parameters can be set in shared-IP zones.

Commitment Level

Identifies the stability of the interface. Many of the parameters in this manual are still evolving and are classified as unstable. For more information, see attributes(5).

Change History

(Optional) Contains a link to the Change History appendix, if applicable.