Solaris Tunable Parameters Reference Manual

Tuning Format

The format for the description of each variable follows:


Variable-Name is the exact name that would be typed in the /etc/system file, or found in the /etc/default/facility file.

Most names are of the form variable where the variable 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 variable within the module consists of the characters to the right of the colon. For example:


This section briefly describes what the variable does or controls.

Data Type

Signed or unsigned short or long integer with the following distinctions:

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

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


What the system uses as the default value.


(Optional) Description of unit type.


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 it can be changed on a running system with the mdb or kadb debuggers. No, if it is a boot time initialization only.


Identifies checks the system applies to the value of the variable either as entered from the /etc/system file or the default value, as well as when the validation is applied.


(Optional) Unstated constraints that might exist on the variable, especially in relation to other variables.

When to Change

Why someone might want to change this value including error messages or return codes.

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 Change History appendix, if applicable.