Configure smart paging for Hyper-v

Smart paging allows us to temporarily use disk resources in place of physical memory.

A lot of people to have the misconception that smart paging is related to the Windows Pagefile.  In actuality, the Windows Pagefile and the Smart Paging File are very different from one another.

We have talked about dynamic memory in front, there are three values in the dynamic memory: RAM, the smallest memory and maximum memory.RAM is the starting memory, the minimum memory is the minimum memory allocated to the virtual machine, the maximum memory is allocated to the virtual machine's largest memory.

In the process of using dynamic memory, usually RAM and minimum memory have different values, the minimum memory is lower than RAM. When multiple virtual machines run at the same time, and use all physical memory. at this time the virtual machine can run normally, but when you need to restart the virtual machine, there is not enough physical memory to provide RAM set values. the virtual machine can run normally, but when you need to restart the virtual machine, there is not enough physical memory to provide RAM set values.  Once the virtual machine starts up and releases the memory, the paging stops immediately.

For example, a Hyper-v Server has 64GB of memory, which can run up to 30 virtual machines, each virtual machine RAM value of 2GB memory, the minimum memory of 512M. When the virtual machine running only 1GB of memory, then 30 virtual machines have been all started and continue to run. At this point Hyper-v will release the useless 30GB of memory, we can be used to run more virtual machines. With the increase of the virtual machine, this 30GB of memory has also been used, and suddenly there is a virtual machine need to restart, but the RAM value of 2GB, while the unused memory only the original operation of the virtual machine 1GB memory, intelligent paging will Will use the hard disk space, to replace the lack of 1GB of memory, so that the virtual machine can start normally.

So why not set the value of RAM and the minimum memory value to the same? Because some operating systems perform a check to make sure that a certain amount of memory is present，and Some operating systems consume more memory at boot time than they do when the system is idle. If you set the same value, it will cause a waste of memory.

The following criteria must be met：

The VM is restarting (not booting from an off state)

No physical memory is available or can be reclaimed from other VMs

You can configure Smart Paging on the Virtual Machine Settings page.