2.15. Performing Virtual Machine-Specific Operations¶

2.15.2.1. Adding New Devices¶

This section provides information on adding new devices to your virtual machines. You can add new virtual devices to your virtual machine using the prlctl set command. The options responsible for adding particular devices are listed in the following table:

For example, you can execute the following command to add a new virtual disk to the virtual machine MyVM:

# prlctl set MyVM --device-add hdd
Creating hdd1 () scsi:1 image='/vz/vmprivate/d35d28e5-11f7-4b3f-9065-8fef6178bc5b/ \
harddisk1.hdd' type='expanded' 65536Mb subtype=virtio-scsi
...

This command creates a new virtual disk with the following default parameters:

• Name: hdd1

• Disk type: SCSI

• Disk subtype: VirtIO SCSI

• Image file name and location: /vz/vmprivate/d35d28e5-11f7-4b3f-9065-8fef6178bc5b/harddisk1.hdd

• Disk format: expanded

• Disk capacity: 65536 MB

You can change some of these parameters with prlctl. For example, to create an 84 GB IDE virtual disk, run

# prlctl set MyVM --device-add hdd --size 84000 --iface ide
Creating hdd2 () ide:0 image='/vz/vmprivate/d35d28e5-11f7-4b3f-9065-8fef6178bc5b/ \
harddisk2.hdd' type='expanded' 84000Mb
...

The virtual disk has been added to your virtual machine. However, before you can use it, you need to initialize it as described in the next subsection.

# prlctl set vm1 --device-add cdrom --image <path_to_image> --iface scsi --subtype hyperv
# prlctl set vm1 --device-add hdd --iface scsi --subtype hyperv

2.15.2.2. Initializing Newly Added Disks¶

After you added a new blank virtual hard disk to the virtual machine configuration, it will be invisible to the operating system installed inside the virtual machine until the moment you initialize it.

# mkfs -t <file system> /dev/hdc1

2.15.2.3. Configuring Virtual Devices¶

You can configure the parameters of an existing virtual device in your virtual machine using the --device-set option of the prlctl set command.

To change the virtual device parameters, do the following:

1. List the VM information to find out the name of the device you wish to configure. For example, to obtain the list of virtual devices in the virtual machine MyVM, run:

   # prlctl list -i MyVM
   ...
   Hardware:
     cpu cpus=2 VT-x accl=high mode=32 ioprio=4 iolimit='0'
     memory 1024Mb
     video 32Mb 3d acceleration=off vertical sync=yes
     hdd0 (+) scsi:0 image='/vz/vmprivate/d35d28e5-11f7-4b3f-9065-8fef6178bc5b/ \
   harddisk.hdd' type='expanded' subtype=virtio-scsi
     hdd1 (+) scsi:1 image='/vz/vmprivate/d35d28e5-11f7-4b3f-9065-8fef6178bc5b/ \
   harddisk1.hdd' type='expanded' subtype=virtio-scsi
     cdrom0 (+) scsi:1 image='' subtype=virtio-scsi
     usb (+)
     net0 (+) dev='vme426f6594' network='Bridged' mac=001C426F6594 card=virtio
   ...
   

   All virtual devices currently available to the virtual machine are listed under Hardware. In our case the virtual machine MyVM has the following devices: 2 CPUs, main memory, video memory, a floppy disk drive, 2 hard disk drives, a CD/DVD-ROM drive, a USB controller, and a network card.

2. Configure the properties of the virtual device. For example, to configure the current type of the virtual disk hdd1 in the virtual machine MyVM from SCSI to IDE, execute:

# prlctl set MyVM --device-set hdd1 --iface ide

To check that the virtual disk type has been successfully changed, use the prlctl list -i command:

# prlctl list -i MyVM | grep hdd1
hdd1 (+) ide:0 image='/vz/vmprivate/d35d28e5-11f7-4b3f-9065-8fef6178bc5b/ \
harddisk1.hdd' type='expanded'

# prlctl set MyVM --device-disconnect cdrom0

# prlctl set MyVM --device-connect cdrom0

2.15.2.4. Deleting Devices¶

You can delete a virtual device that you do not need any more in your virtual machine using the --device-del option of the prlctl set command. The options responsible for removing particular devices are listed in the following table:

To remove a virtual device, do the following:

1. List the VM information to find out the name of the device you wish to delete. For example, to obtain the list of virtual devices in the virtual machine MyVM, run:

   # prlctl list --info MyVM
   ...
   Hardware:
     cpu cpus=2 VT-x accl=high mode=32 ioprio=4 iolimit='0'
     memory 1024Mb
     video 32Mb 3d acceleration=off vertical sync=yes
     hdd0 (+) scsi:0 image='/vz/vmprivate/d35d28e5-11f7-4b3f-9065-8fef6178bc5b/ \
   harddisk.hdd' type='expanded' subtype=virtio-scsi
     hdd1 (+) scsi:1 image='/vz/vmprivate/d35d28e5-11f7-4b3f-9065-8fef6178bc5b/ \
   harddisk1.hdd' type='expanded' subtype=virtio-scsi
     cdrom0 (+) scsi:1 image='' subtype=virtio-scsi
     usb (+)
     net0 (+) dev='vme426f6594' network='Bridged' mac=001C426F6594 card=virtio
   ...
   

2. Remove the virtual device from your virtual machine. For example, to remove the virtual disk hdd1 from the virtual machine MyVM, execute:

   # prlctl set MyVM --device-del hdd1
   

If you do not want to permanently delete a virtual device, you can temporarily disconnect it from the virtual machine using the --disable option.

2.15.4.1. Assigning USB Devices to Virtual Machines¶

To assign a USB device to a VM, specify two parameters:

1. The USB device ID that you can get by running the prlsrvctl usb list command. For example:

   # prlsrvctl usb list
   Sony - Storage Media     '3-2|054c|05ba|high|--|CB070B7B49A7C06786|3'
   

2. The virtual machine UUID that you can obtain by running the prlctl list -a command. For example:

   # prlctl list -a
   UUID                                    STATUS       IP_ADDR         T  NAME
   {d8d516c9-dba3-dc4b-9941-d6fad3767035}  stopped      10.10.100.1     VM MyVM
   

Once you know the necessary parameters, do the following:

1. Make sure the VM is stopped. For example:

   # prlctl list -i MyVM | grep State
   State: stopped
   

2. Assign the USB device to the VM using the prlsrvctl usb set command. For example:

   # prlsrvctl usb set '3-2|054c|05ba|high|--|CB070B7B49A7C06786|3' \
   {d8d516c9-dba3-dc4b-9941-d6fad3767035}
   

   This command assigns the USB device Sony - Storage Media with ID '3-2|054c|05ba|high|--|CB070B7B49A7C06786|3' to the virtual machine MyVM with UUID {d8d516c9-dba3-dc4b-9941-d6fad3767035. When running the command, remember to put the USB device ID in single quotes and the VM UUID in curly brackets.

To check that the USB device has been successfully assigned to the VM, use the prlsrvctl usb list command. For example:

# prlsrvctl usb list
Sony - Storage Media     '3-2|054c|05ba|high|--|CB070B7B49A7C06786|3' \
{d8d516c9-dba3-dc4b-9941-d6fad3767035}

The command output shows that the USB device Sony - Storage Media will be automatically connected to the VM with UUID {d8d516c9-dba3-dc4b-9941-d6fad3767035} every time you start this VM and connect the device to the hardware node.

To remove the assignment, use the prlsrvctl usb del command. For example:

# prlsrvctl usb del '3-2|054c|05ba|high|--|CB070B7B49A7C06786|3'

2.15.4.2. Assigning PCI Devices to Virtual Machines¶

Assigning PCI devices to VMs is available only on server platforms that support Intel Virtualization Technology for Directed I/O (VT-d) or AMD I/O Virtualization Technology (IOMMU). This feature must be supported by both the motherboard chipset and CPU. For a list of IOMMU-supporting hardware, see this Wikipedia article.

Before assigning PCI devices, prepare your system as follows:

1. Enable the CPU virtualization extensions (VT-d or AMD IOMMU) in the host BIOS.

2. Enable the IOMMU support in the kernel:

   1. In the /etc/default/grub file, locate the GRUB_CMDLINE_LINUX line and add within the quotes either intel_iommu=on iommu=pt or amd_iommu=pt, depending on the platform. For example, on an Intel-based system, the line will be:

      GRUB_CMDLINE_LINUX="crashkernel=auto rd.lvm.lv=virtuozzo/root quiet \
      intel_iommu=on iommu=pt"
      

   2. Regenerate the grub config file:

      • On a BIOS-based system, run:

        # grub2-mkconfig -o /etc/grub2.cfg
        

      • On a UEFI-based system, run:

        # grub2-mkconfig -o /etc/grub2-efi.cfg
        

3. Reboot the system to apply the changes.

To check that IOMMU is enabled, run one of the following commands:

• On an Intel-based system:

  # dmesg | grep "Virtualization Technology for Directed I/O"
  [ 0.902214] DMAR: Intel(R) Virtualization Technology for Directed I/O
  

• On an AMD-based system:

  # dmesg | grep AMD-Vi
  AMD-Vi: Enabling IOMMU at 0000:00:00.2 cap 0x40
  AMD-Vi: Lazy IO/TLB flushing enabled
  AMD-Vi: Initialized for Passthrough Mode
  

Now you can proceed to assign the PCI device to a VM. Do the following:

1. Find the ID of the desired device in the output of the prlsrvctl info | grep pci command. For example:

   # prlsrvctl info | grep pci
   pci X540 Ethernet Controller '8:0:1:8086.1521' assignment=host
   <...>
   

2. Make sure the VM that you will assign the PCI device to is stopped. For example:

   # prlctl list -i MyVM | grep State
   State: stopped
   

3. Assign the PCI device to the VM. For example, to assign the network adapter X540 Ethernet Controller with the ID '8:0:1:8086.1521' to the virtual machine MyVM, run:

   # prlctl set MyVM --device-add pci --device '8:0:1:8086.1521'
   

To check that the PCI device has been successfully assigned to the VM, run the following command:

# prlctl list -i MyVM | grep pci
pci0 (+) 'Intel Corporation Ethernet Controller 10-Gigabit X540-AT2' '8:0:1'

Now the PCI device X540 Ethernet Controller will automatically connect to the MyVM virtual machine every time this VM is started and the device is connected to the hardware node.

To remove the assignment, use the prlctl set --device-del command:

# prlctl set --device-del pci0

2.15.4.3. Using PCI I/O Virtualization¶

Single Root I/O Virtualization (SR-IOV) is a specification that allows a single physical PCI device to appear as multiple virtual devices and thus be shared by multiple virtual machines. Virtuozzo Hybrid Server supports assigning Virtual Functions of SR-IOV-capable PCI devices, namely network adapters, to virtual machines.

Before creating virtual PCI devices, make sure the following requirements are met:

1. The system is prepared to support IOMMU as described in Assigning PCI Devices to Virtual Machines.

2. SR-IOV is enabled in the system BIOS.

To create virtual network adapters, or Virtual Functions of a network adapter, you need to specify their number in the /sys/class/net/<device_name>/device/sriov_numvfs file. For example, to create two Virtual Functions of the Ethernet adapter enp2s0, run:

# echo 2 > /sys/class/net/enp2s0/device/sriov_numvfs

To ensure that the intended number of Virtual Functions is persistent across server reboots, create a udev rule similar to the following:

# vi /etc/udev/rules.d/enp2s0.rules
ACTION=="add", SUBSYSTEM=="net", ENV{ID_NET_DRIVER}=="ixgbe",
ATTR{device/sriov_numvfs}="2"

where enp2s0 is the name of the network adapter, ixgbe is the name of the network driver in use, and 2 is the number of Virtual Functions to be created at boot time.

The maximum number of Virtual Functions supported by a network device can be queried by reading the /sys/class/net/<device_name>/device/sriov_totalvfs file. For example, for the Ethernet adapter enp2s0, run:

# cat /sys/class/net/enp2s0/device/sriov_totalvfs
63

To check that Virtual Functions have been successfully created, execute:

# prlsrvctl info | grep Ethernet
pci  X540 Ethernet Controller '8:0:1:8086.1521' assignment=host
pci  X540 Ethernet Controller Virtual Function '9:10:4:8086.1520' assignment=host
pci  X540 Ethernet Controller Virtual Function '9:10:0:8086.1520' assignment=host

After creating virtual network adapters, you can assign them to VMs as described in Assigning PCI Devices to Virtual Machines. For them to work properly, install appropriate network drivers inside the VMs.