Virtual Machines

How to set up a Virtual Machine.

  4 minute read

A Virtual Machine (VM) is an environment on a host computer that can be used as if it were a separate physical computer. VMs can be used to run multiple operating systems simultaneously on a single computer. Operating systems running inside a VM see emulated virtual hardware rather than the actual hardware of the host computer. This provides more isolation than Jails, but a VM will consume more system resources. A portion of system RAM is assigned to each VM, and each VM uses a zvol for storage. While a VM is running, these resources are not available to the host computer or other VMs.

TrueNAS VMs use the bhyve virtual machine software. This type of virtualization requires an Intel processor with Extended Page Tables (EPT) or an AMD processor with Rapid Virtualization Indexing (RVI) or Nested Page Tables (NPT). VMs cannot be created unless the host system supports these features.

To verify that an Intel processor has the required features, open the Shell and run grep VT-x /var/run/dmesg.boot. If the EPT and UG features are shown, this processor can be used with bhyve.

To verify that an AMD processor has the required features, open the Shell and run grep POPCNT /var/run/dmesg.boot. If the output shows the POPCNT feature, this processor can be used with bhyve. Note that AMD K10 “Kuma” processors include POPCNT but do not support NRIS, which is required for use with bhyve. Production of these processors ceased in 2012-2013.

Creating a Virtual Machine

Before creating the virtual machine, you will need an installer .iso or image file for the operating system you intend to install and a storage pool available for both the virtual disk and operating system install file.

To create a new VM, go to Virtual Machines and click Add. Configure each category of the VM according to your specifications, starting with the Operating System.



Notes about the VM options:

  • The Grub Boot Method is not supported by Windows guest operating systems.
  • Compare the recommended specifications for your guest operating system with the available host system resources when allocating Virtual CPUs, Cores, Threads, and Memory Size.
  • Avoid allocating too much memory to a VM. Activating a VM that has all available memory allocated to it can slow the host system or prevent other VMs from starting.
  • AHCI is the recommended Disk Type for Windows VMs.
  • The VirtIO Network Interface requires that the chosen guest operating system support VirtIO paravirtualized network drivers.

Adding and Removing Devices

After the VM is created, you can add and remove virtual devices by expanding the VM entry in Virtual Machines and clicking DEVICES.



Notes about devices:

  • The virtual machine will attempt to boot from devices according to the Device Order, starting with 1000, then ascending.
  • CD-ROM devices allowing booting a VM from a CD-ROM image like an installation CD. The CD image must be available in the system storage.

Managing the Virtual Machine

After creating the VM and configuring any devices for it, you can manage the VM by expanding its entry in Virtual Machines



Options for VNC or SERIAL connections are available after activating the VM. If the VNC connection screen appears garbled, try adjusting the VNC device resolution.

Using the State toggle or clicking the STOP follows a standard shut down procedure to cleanly shut down the running VM. Clicking the POWER OFF immediately halts and deactivates the VM, similar to unplugging a computer.


Last modified October 7, 2020: Update virtual-machines.md (64cf38b2)