Memory Usage Problems

The amount of Mac's physical memory required for each virtual machine operation can be represented as follows:

Virtual Machine Memory = Guest OS Memory + Video Memory + Virtual Machine Monitor Memory

• Guest OS Memory is the amount of RAM available to your guest operating system. You can configure the guest OS memory amount in the CPU & Memory pane of the virtual machine configuration dialog.
• Video Memory is the amount of physical memory available to the virtual machine's video card. You can adjust the video memory amount in the Graphics pane of the virtual machine configuration dialog.
• Virtual Machine Monitor is the module responsible for the guest operating system virtualization. It consumes memory to perform operations of guest virtual devices and performs virtual paging emulation. The amount of memory required for the Virtual Machine Monitor operation depends on the guest OS and varies from 50 MB to 200 MB.

Memory Overcommitment

If you have several virtual machines running simultaneously and you are trying to start one more virtual machine, you may come across the memory over commit. If so, Parallels Desktop informs you with the corresponding message. If you start one more virtual machine, this may significantly slow down all your virtual machines. To solve this problem, you can:

• Stop one or several of your running virtual machines; or
• Edit your virtual machines' configurations so they consume less memory.