Basic VM Management
4 minute read.Last Modified 2023-11-30 10:15 EST
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 consumes more system resources.
A portion of system RAM and a new zvol is assigned to each VM. 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.
Before creating the virtual machine, you need an installer
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.
For information on the Wizard screens and settings, see Virtual Machines.
- The Grub boot method is not supported by Windows as the guest operating systems.
- Compare the recommended specifications for your guest operating system with the available host system resources when allocating values in 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.
- VirtIO as network interface requires that the chosen guest operating system support VirtIO paravirtualized network drivers.
After creating the VM, you can add and remove virtual devices by expanding the VM entry in Virtual Machines and clicking the device_hub Devices option.
- The virtual machine attempts to boot from devices according to the the Device Order setting, starting with 1000, then ascending.
- The CD-ROM device option allows booting a VM from a CD-ROM image like an installation CD. The CD image must be available in the system storage.
After creating the VM and configuring any devices for it, manage the VM by expanding its entry in Virtual Machines.
Options for settings_ethernet or keyboard_arrow_right 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 stop follows a standard shut down procedure to do a clean shut down the running VM. Clicking power_settings_new immediately halts and deactivates the VM, similar to unplugging a computer.
If the VM you created has no guest OS installed, the VM State toggle and stop button might not function as expected. These buttons try to send an ACPI power-down command to the VM operating system, but since no OS is installed, the commands time out. Use the POWER OFF button instead.