Oracle Solaris Tunable Parameters Reference Manual



Specifies the preferred amount of memory to be free at all times on the system.

Data Type

Unsigned integer


lotsfree / 2


The minimum value is 256 Kbytes or 1/128th of physical memory, whichever is greater, expressed as pages using the page size returned by getpagesize.

The maximum value is the number of physical memory pages. The maximum value should be no more than 15 percent of physical memory. The system does not enforce this range other than that described in the Validation section.




Yes, unless dynamic reconfiguration operations that add or delete memory occur. At that point, the value is reset to the value provided in the /etc/system file or calculated from the new physical memory value.


If desfree is greater than lotsfree, desfree is set to lotsfree / 2. No message is displayed.


The relationship of lotsfree being greater than desfree, which is greater than minfree, should be maintained at all times.

Side Effects

Several side effects can arise from increasing the value of this parameter. When the new value nears or exceeds the amount of available memory on the system, the following can occur:

  • Asynchronous I/O requests are not processed, unless available memory exceeds desfree. Increasing the value of desfree can result in rejection of requests that otherwise would succeed.

  • NFS asynchronous writes are executed as synchronous writes.

  • The swapper is awakened earlier, and the behavior of the swapper is biased towards more aggressive actions.

  • The system might not prefault as many executable pages into the system. This side effect results in applications potentially running slower than they otherwise would.

When to Change

For systems with relatively static workloads and large amounts of memory, lower this value. The minimum acceptable value is 256 Kbytes, expressed as pages using the page size returned by getpagesize.

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