Dynamic Memory allows you to set a range of memory to allocate to your VMs. Hyper-V 2012 has added a Startup RAM feature to allow you to allocate more memory at startup than you might need for normal operations, which can speed up reboots.
What’s really cool about dynamic memory is that you can change it while the VM is running. There are limitations, and you can’t change all of the settings, but you can change the minimum and maximum settings, as shown here:
But what if you are running something where you don’t want to use dynamic memory, or where dynamic memory is not recommended? What if you want to set a static amount of memory, but still be able to give it more memory without shutting it down?
Simple. Just set the VM to use dynamic memory, and set the minimum and maximum amounts to the same amount! If you need to increase the memory later, just change the maximum value to the new, higher amount. Note that you won’t be able to increase the minimum amount while it is running, but this will buy you some time until the next shutdown, where you can set the minimum and maximum amounts to the new higher amount.