Seems like there’s always been a lot of controversy about page files, where to put them, how big they should be, should you Windows manage them, should you put it on a separate partition and on and on. With virtualized servers you can still argue all of those points except one – you should not let Windows manage them. You have to take the reigns.
Why? Because of the way that windows is designed. When self-calculating the size of the page file Windows looks at the hardware to see how much memory is installed. It then sets up a page file for a maximum of about 1.5 times that installed amount. It starts out smaller and is allowed to grow creating a fragmented mess, but the topic of fragmented mess is of one of the controversial elements I mentioned earlier. Let’s look at a small example:
The parent system has 32GB of installed memory. Left to it’s own it will then setup 32GB of page file.
Now let’s say this server has 4 virtual machines. Each of which will setup their own page file. And only 4GB of installed memory is left over for the parent. What is a server with 4GB of RAM going to do with 32GB of page file? We need to reduce the page file size to 4GB. I also like to make that size fixed to reduce fragmentation.
After you have this one set. Take a look at your virtual machines and set those according to the installed memory allocated to each.