Memory Tab

The settings on the Memory tab affect the performance of both the virtual machine and the overall system:

•	The Reserved memory section lets you specify how much of the host computer’s RAM should be reserved to accommodate all the powered-on virtual machines it hosts. For more information, see Reserved Memory Section.

Then in the virtual machine settings editor (choose VM > Settings > Memory), you can specify, for a particular virtual machine, how much memory to allocate for that virtual machine.

•	The Additional memory section lets you adjust how the host operating system’s memory manager swaps virtual machines out of physical RAM. For more information, see Additional Memory Section.


Note On Linux, you must be running Workstation as root in order to change the settings on the Memory tab of the preferences editor.

Reserved Memory Section

The sum of the memory of all currently running virtual machines plus overhead for the Workstation processes cannot exceed the amount of physical memory on the host minus some memory that must be kept available for the host.

The reserved memory setting specifies a maximum amount of host RAM that Workstation is allowed to use, but this memory is not allocated in advance. Even if multiple virtual machines are running at the same time, Workstation might be using only a fraction of the RAM you specify here. Any unused RAM is available for use by other applications. If all the RAM you specify here is in use by one or more virtual machines, the host operating system cannot use this memory itself or allow other applications to use it.

The amount of RAM actually used for a particular virtual machine varies as a virtual machine runs. If multiple virtual machines run simultaneously, they work together to manage the memory.

The recommended amount of RAM to specify for all running virtual machines is calculated on the basis of the host computer’s physical memory and is displayed in the memory settings control (choose Edit > Preferences > Memory). If you want to use more or less physical memory, use the slider to change the amount.

If you set this value too high, the host might thrash if other applications are run on the host. If you set this value too low, virtual machines might perform poorly, and you will not be able to run as many virtual machines at once.

For information on setting memory for a single virtual machine, see Memory Settings Panel.

Additional Memory Section

Workstation limits the number of virtual machines that can run at once based on the amount of memory specified in the preferences editor. This prevents virtual machines from causing each other to perform poorly.

To increase the number or memory size of virtual machines that can run, adjust the amount of virtual machine memory that the host operating system can swap to disk. To change this setting, choose Edit > Preferences > Memory and choose an option under Additional memory.

Select one of the following options:

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Fit all virtual machine memory into reserved host RAM — Strictly apply the reserved memory limit set at the top of the panel. This setting imposes the tightest restrictions on the number and memory size of virtual machines that can run at a given time. Because the virtual machines are running entirely in RAM, they have the best possible performance.

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Allow some virtual machine memory to be swapped — Allow the host operating system to swap a moderate amount of virtual machine memory to disk if necessary. This setting allows you to increase the number or memory size of virtual machines that can run on the host computer at a given time. It might also result in reduced performance if virtual machine memory must be shifted between RAM and disk.

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Allow most virtual machine memory to be swapped — Allow the host operating system to swap as much virtual machine memory to disk as necessary and possible. This setting allows you to run even more virtual machines with even more memory than the intermediate setting does. In this case, performance might be reduced if virtual machine memory must be shifted between RAM and disk.

If you try to power on a virtual machine and there is not enough memory available, Workstation displays a warning message. To try to power on the virtual machine using the available memory, click OK. If you do not want to power on the virtual machine, click Cancel. You might also try closing the console in which you tried to power on the virtual machine, and then open a new console and try powering on again.