Andy Fox | 5 July 2012
In the vSphere 5 materials, when discussing the vmkernel swap file per vm, there is reference to there being swap files (in plural). In addition to the vmkernel swap file, vSphere 5 introduces a new swap file for the virtual machine overhead (vmx).
The vmkernel normally reserves the memory overhead for each vm in addition to any memory reservation you have defined, so normally should not need to swap the overhead. However, there are situations when the host is under memory pressure where having a swap file supporting the memory for the vmx process, allowing parts of memory to be swapped out may be of benefit.
So in vSphere 5, vmx swap has been introduced to reduce the memory footprint of the vmx process by up to 80%.
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