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Adding and Managing VMs

  7 minute read.

Last Modified 2022-10-11 12:06 EDT

A Virtual Machine (VM) is an environment on a host computer that you can use as if it were a separate, physical computer. Users can use VMs to run multiple operating systems simultaneously on a single computer. Operating systems running inside a VM see emulated virtual hardware rather than the host computer physical hardware. VMs provide more isolation than Jails but also consumes more system resources.

TrueNAS assigns a portion of system RAM and a new zvol to each VM. While a VM is running, these resources are not available to the host computer or other VMs.

TrueNAS VMs use the KVM virtual machine software. This type of virtualization requires an x86 machine running a recent Linux kernel on an Intel processor with VT (virtualization technology) extensions or an AMD processor with SVM extensions (also called AMD-V). Users cannot create VMs unless the host system supports these features.

To verify that you have Intel VT or AMD-V, open the Shell and run egrep '^flags.*(vmx|svm)' /proc/cpuinfo. If device information appears, your system has VT. You can also check the processor model name (in /proc/cpuinfo) on the vendor’s website.

Creating a Virtual Machine

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

To create a new VM, go to Virtualization and click Add or Add Virtual Machines if you have not yet added a virtual machine to your system. Configure each category of the VM according to your specifications, starting with the Operating System.


For more information see Virtualization Screens for more information on virtual machine screen settings.

Additional notes:

Compare the recommended specifications for your guest operating system with the available host system resources when allocating virtual CPUs, cores, threads, and memory size.

Do not allocate too much memory to a VM. Activating a VM with all available memory allocated to it can slow the host system or prevent other VMs from starting.

We recommend using AHCI as the Disk Type for Windows VMs.

The VirtIO network interface requires a guest OS that supports VirtIO paravirtualized network drivers.

iXsystems does not have a list of approved GPUs at this time but does have drivers and basic support for the list of nvidia Supported Products.

Adding and Removing Devices

After creating the VM, add and remove virtual devices by expanding the VM entry on the Virtual Machines screen and clicking Devices.


Device notes:

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

Managing a Virtual Machine

After creating the VM and configuring devices for it, manage the VM by expanding the entry on the Virtual Machines screen.


An active VM displays options for Display and Serial Shell connections.

If the display connection screen appears distorted, try adjusting the display device resolution.

Use the State toggle or click Stop to follow a standard procedure to do a clean shutdown of the running VM. Click Power Off to halt and deactivate the VM, which is 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. The State toggle and Stop button send an ACPI power down command to the VM operating system, but since an OS is not installed, these commands time out. Use the Power Off button instead.

Installing an OS

When the VM is configured in TrueNAS and has an OS .iso, file attached, you can start the VM and begin installing the operating system.

Some operating systems can require specific settings to function properly in a virtual machine. For example, vanilla Debian can require advanced partitioning when installing the OS. Refer to the documentation for your chosen operating system for tips and configuration instructions.

Here is an example of installing a Debian OS in a TrueNAS VM. The Debian .iso is uploaded to the TrueNAS system and attached to the VM as a CD-ROM device.

  1. Click on the Virtualization menu then click ADD to start the VM creation process using the wizard.


Operating System:

  • Guest Operating System: Linux
  • Name: debianVM
  • Description: Debian VM

CPU and Memory:

  • Change the memory size to 1024 MiB.


  • Select Create new disk image.
  • Select the Zvol Location.
  • Change the size to 30 GiB.

Network Interface:

  • Attach NIC: Select the physical interface to associate with the VM.

Installation Media:

  • In this case the installation ISO is uploaded to /mnt/tank2/isostorage/. Click on the installation ISO, debian-11.0.0-amd64-netinst.iso.
  • If the ISO is or was not uploaded, you need to set Upload an installer image file. Select a dataset to store the ISO, click Choose file, then click Upload. Wait for the upload to complete (this can take some time).


  • Leave the default values.

Confirm Options

  • Verify the information is correct and then click Save.
  1. After the VM is created, start it by expanding the VM entry (select the down-pointing arrow to the right of the VM name) and click Start.

  2. Click Display to open a virtual monitor to the VM and see the Debian Graphical Installation screens.

Debian Graphical Install

  • Press Return to start the Debian Graphical Install.
  • Language: English
  • Location: United States
  • Keymap: American English

Installation begins

  • Continue if the network configuration fails.
  • Do not configure the network at this time.
  • Enter a name in Hostname.
  • Enter the root password and re-enter the root password.
  • Enter a name in New User.
  • Select the username for your account (it should already be filled in).
  • Enter and re-enter the password for the user account.
  • Choose the time zone, Eastern in this case.

Disk detection should begin

  • Partition disks: select Guided - use entire disk.
  • Select the available disk.
  • Select All files in one partition (recommended for new users).
  • Select Finish partitioning and write changes to disk.
  • Select Yes to Write the changes to disks?.

Installing the base system

  • Select No to the question Scan extra installation media.
  • Select Yes when asked Continue without a network mirror.

Installing software

  • Select No when asked Participate in the package usage survey.
  • Select Standard system utilities.
  • Click Continue when the installation finishes.

After the Debian installation finishes, close the display window.

  1. Remove the device. In the expanded section for the VM, click Power Off to stop the new VM.

    a. Click Devices.

    b. Remove the CD-ROM from the devices by clicking the   and selecting Delete. Click Delete Device.

  2. Return to the Virtual Machines screen and expand the new VM again.

  3. Click Start.

  4. Click Display.

The grub file does not run when you start the VM, you can do this manually after each start. At the shell prompt:

  1. Type FS0: Return.
  2. Type cd EFI Return.
  3. Type cd Debian Return.
  4. Type grubx64.efi Return.

To ensure it starts automatically, you create the startup.nsh file at the root directory on the vm. To create the file:

  1. Go to the Shell.

  2. At the shell prompt type edit startup.nsh.

  3. In the editor type:

  • Type FS0: Return.
  • Type cd EFI Return.
  • Type cd Debian Return.
  • Type grubx64.efi Return.
  • Use the Control+s keys (Command+s for Mac OS) then Return.
  • Use the Control+q keys to quit.
  1. Close the display window

  2. To test if it now boots up on startup:

    • Power off the VM.
    • Click Start.
    • Click Display.
    • Log into your Debian VM.

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