Special Solaris tune and var Structures

Solaris tunable parameters come in a variety of forms. The tune structure defined in the/usr/include/sys/tuneable.h file is the runtime representation of tune_t_fsflushr, tune_t_minarmem, and tune_t_flkrec. After the kernel is initialized, all references to these variables are found in the appropriate field of the tune structure.

Various documents (for example, previous versions of Solaris System Administration Guide, Volume 2) have stated that the proper way to set parameters in the tune structure is to use the syntax, tune:field-name where field-name is replaced by the actual parameter name listed above. This process silently fails. The proper way to set parameters for this structure at boot time is to initialize the special parameter that corresponds to the desired field name. The system initialization process then loads these values into the tune structure.

A second structure into which various tunable parameters are placed is the var structure named v. You can find the definition of a var structure in the /usr/include/sys/var.h file. The runtime representation of variables such as autoup and bufhwm is stored here.

Do not change either the tune or v structure on a running system. Changing any field in these structures on a running system might cause the system to panic.