Check manual page of mem_win

Memory Usage

Included in	All Checkmk editions
Source Code License	Open Source
Supported Agents	Windows

This check measures the current usage of physical RAM and virtual memory.

Due to how Windows optimizes memory management, physical memory is in practice almost always fully utilized. The Memory usage this check displays says how much memory is actually required by processes, in contrast to caches that could be freed if the need arises.

In the same way, Windows may hold data in RAM and pagefile at the same time or it may hold data in the pagefile even if there is RAM available, when it determines this may improve performance.

Used virtual memory tells us how much of the total memory (RAM + page file) is really required, ignoring overlap and caches.

Used virtual memory minus used RAM is approximately the amount of the pagefile used for "relevant" data, but further optimizations may lead to offsets (to the point where used virtual memory - RAM can be negative).

The used virtual memory metric is determined using the fields 'ullTotalPageFile' (current committed memory limit for the system or the current process, whichever is smaller) and 'ullAvailPageFile' (maximum amount of memory the current process can commit) of the MEMORYSTATUSEX structure as returned by the windows API function 'GlobalMemoryStatusEx'.

Discovery

One service is created for each host that provides data about the page file. If that information is missing, a Unix-like system is assumed and the check mem.used is creating one service instead.