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Chapter 10. Viewing information about virtual machines

When you need to adjust or troubleshoot any aspect of your virtualization deployment on RHEL 10, the first step you need to perform usually is to view information about the current state and configuration of your virtual machines (VMs). To do so, you can use the command line or the web console. You can also view the information in the VM’s XML configuration.

To retrieve information about virtual machines (VMs) on your host and their configurations, you can use the virsh command-line utility.

Procedure

  • To obtain a list of VMs on your host: 

    # virsh list --all
Id   Name              State
----------------------------------
1    testguest1             running
-    testguest2             shut off
-    testguest3             shut off
-    testguest4             shut off
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  • To obtain basic information about a specific VM: 

    # virsh dominfo _testguest1
Id:             1
Name:           testguest1
UUID:           a973666f-2f6e-415a-8949-75a7a98569e1
OS Type:        hvm
State:          running
CPU(s):         2
CPU time:       188.3s
Max memory:     4194304 KiB
Used memory:    4194304 KiB
Persistent:     yes
Autostart:      disable
Managed save:   no
Security model: selinux
Security DOI:   0
Security label: system_u:system_r:svirt_t:s0:c486,c538 (enforcing)
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  • To obtain the complete XML configuration of a specific VM: 

    # virsh dumpxml testguest2

<domain type='kvm' id='1'>
  <name>testguest2</name>
  <uuid>a973434f-2f6e-4ěša-8949-76a7a98569e1</uuid>
  <metadata>
[...]
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    For an annotated example of a VM’s XML configuration, see Sample virtual machine XML configuration

  • For information about a VM’s disks and other block devices: 

    # virsh domblklist testguest3
 Target   Source
---------------------------------------------------------------
 vda      /var/lib/libvirt/images/testguest3.qcow2
 sda      -
 sdb      /home/username/Downloads/virt-p2v-1.36.10-1.el7.iso
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    For instructions on managing a VM’s storage, see Managing storage for virtual machines.

  • To obtain information about a VM’s file systems and their mountpoints: 

    # virsh domfsinfo testguest3
Mountpoint   Name   Type   Target
------------------------------------
 /            dm-0   xfs   vda
 /boot        vda2   xfs   vda
 /boot/efi    vda1   vfat  vda
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  • To obtain more details about the vCPUs of a specific VM: 

    # virsh vcpuinfo testguest4
VCPU:           0
CPU:            3
State:          running
CPU time:       103.1s
CPU Affinity:   yyyy

VCPU:           1
CPU:            0
State:          running
CPU time:       88.6s
CPU Affinity:   yyyy
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    To configure and optimize the vCPUs in your VM, see Optimizing virtual machine CPU performance.

  • To list all network interfaces of a specific VM: 

    # virsh domiflist testguest5
Interface   Type      Source    Model    MAC
-------------------------------------------------------------
 vnet0       network   default   virtio   52:54:00:ad:23:fd
 vnet1       bridge    br0       virtio   52:54:00:40:d4:9d
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    For details about network interfaces, VM networks, and instructions for configuring them, see Configuring virtual machine network connections.

  • For instructions on viewing information about storage pools and storage volumes on your host, see Viewing virtual machine storage information by using the CLI.

By using the web console, you can access a virtualization overview that contains summarized information about available virtual machines (VMs), disks, storage pools, and networks.

Prerequisites

Procedure

  • Click Virtual Machines in the web console’s side menu.

    A dialog box appears with information about the available storage pools, available networks, and the VMs to which the web console is connected.

The information includes the following:

  • Storage Pools - The number of storage pools, active or inactive, that can be accessed by the web console and their state.
  • Networks - The number of networks, active or inactive, that can be accessed by the web console and their state.
  • Name - The name of the VM.
  • Connection - The type of libvirt connection, system or session.
  • State - The state of the VM.
  • Resource usage - Memory and virtual CPU usage of the VM.
  • Disks - Detailed information about disks assigned to the VM.
Note

Changes to the virtual network interface settings take effect only after restarting the VM.

Additionally, MAC address can only be modified when the VM is shut off.

10.3. Sample virtual machine XML configuration
Copier lien

The XML configuration of a VM, also referred to as a domain XML, determines the VM’s settings and components. The following table shows sections of a sample XML configuration of a virtual machine (VM) and explains the contents.

To obtain the XML configuration of a VM, you can use the virsh dumpxml command followed by the VM’s name. 

# virsh dumpxml testguest1
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Expand
Table 10.1. Sample XML configuration
Domain XML SectionDescription
<domain type='kvm'>
 <name>Testguest1</name>
 <uuid>ec6fbaa1-3eb4-49da-bf61-bb02fbec4967</uuid>
 <memory unit='KiB'>1048576</memory>
 <currentMemory unit='KiB'>1048576</currentMemory>
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This is a KVM virtual machine called Testguest1, with 1024 MiB allocated RAM. 

 <vcpu placement='static'>1</vcpu>
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The VM is allocated with a single virtual CPU (vCPU).

For information about configuring vCPUs, see Optimizing virtual machine CPU performance. 

 <os>
  <type arch='x86_64' machine='pc-q35-rhel10.0.0'>hvm</type>
  <boot dev='hd'/>
 </os>
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The machine architecture is set to the AMD64 and Intel 64 architecture, and uses the Intel Q35 machine type to determine feature compatibility. The OS is set to be booted from the hard disk drive. 

 <features>
  <acpi/>
  <apic/>
 </features>
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The acpi and apic hypervisor features are disabled. 

 <cpu mode='host-model' check='partial'/>
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The host CPU definitions from capabilities XML (obtainable with virsh domcapabilities) are automatically copied into the VM’s XML configuration. Therefore, when the VM is booted, libvirt picks a CPU model that is similar to the host CPU, and then adds extra features to approximate the host model as closely as possible. 

 <clock offset='utc'>
  <timer name='rtc' tickpolicy='catchup'/>
  <timer name='pit' tickpolicy='delay'/>
  <timer name='hpet' present='no'/>
 </clock>
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The VM’s virtual hardware clock uses the UTC time zone. In addition, three different timers are set up for synchronization with the QEMU hypervisor. 

 <on_poweroff>destroy</on_poweroff>
 <on_reboot>restart</on_reboot>
 <on_crash>destroy</on_crash>
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When the VM powers off, or its OS terminates unexpectedly, libvirt terminates the VM and releases all its allocated resources. When the VM is rebooted, libvirt restarts it with the same configuration. 

 <pm>
  <suspend-to-mem enabled='no'/>
  <suspend-to-disk enabled='no'/>
 </pm>
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The S3 and S4 ACPI sleep states are disabled for this VM. 

<devices>
 <emulator>/usr/libexec/qemu-kvm</emulator>
 <disk type='file' device='disk'>
  <driver name='qemu' type='qcow2'/>
  <source file='/var/lib/libvirt/images/Testguest.qcow2'/>
  <target dev='vda' bus='virtio'/>
 </disk>
 <disk type='file' device='cdrom'>
  <driver name='qemu' type='raw'/>
  <target dev='sdb' bus='sata'/>
  <readonly/>
 </disk>
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The VM uses the /usr/libexec/qemu-kvm binary file for emulation and it has two disk devices attached.

The first disk is a virtualized hard-drive based on the /var/lib/libvirt/images/Testguest.qcow2 stored on the host, and its logical device name is set to vda.

The second disk is a virtualized CD-ROM and its logical device name is set to sdb. 

  <controller type='usb' index='0' model='qemu-xhci' ports='15'/>
  <controller type='sata' index='0'/>
  <controller type='pci' index='0' model='pcie-root'/>
  <controller type='pci' index='1' model='pcie-root-port'>
   <model name='pcie-root-port'/>
   <target chassis='1' port='0x10'/>
  </controller>
  <controller type='pci' index='2' model='pcie-root-port'>
   <model name='pcie-root-port'/>
   <target chassis='2' port='0x11'/>
  </controller>
  <controller type='pci' index='3' model='pcie-root-port'>
   <model name='pcie-root-port'/>
   <target chassis='3' port='0x12'/>
  </controller>
  <controller type='pci' index='4' model='pcie-root-port'>
   <model name='pcie-root-port'/>
   <target chassis='4' port='0x13'/>
  </controller>
  <controller type='pci' index='5' model='pcie-root-port'>
   <model name='pcie-root-port'/>
   <target chassis='5' port='0x14'/>
  </controller>
  <controller type='pci' index='6' model='pcie-root-port'>
   <model name='pcie-root-port'/>
   <target chassis='6' port='0x15'/>
  </controller>
  <controller type='pci' index='7' model='pcie-root-port'>
   <model name='pcie-root-port'/>
   <target chassis='7' port='0x16'/>
  </controller>
  <controller type='virtio-serial' index='0'/>
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The VM uses a single controller for attaching USB devices, and a root controller for PCI-Express (PCIe) devices. In addition, a virtio-serial controller is available, which enables the VM to interact with the host in a variety of ways, such as the serial console.

For more information about virtual devices, see Types of virtual devices. 

 <interface type='network'>
  <mac address='52:54:00:65:29:21'/>
  <source network='default'/>
  <model type='virtio'/>
 </interface>
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A network interface is set up in the VM that uses the default virtual network and the virtio network device model.

For information about configuring the network interface, see Optimizing virtual machine network //performance. 

  <serial type='pty'>
   <target type='isa-serial' port='0'>
    <model name='isa-serial'/>
   </target>
  </serial>
  <console type='pty'>
   <target type='serial' port='0'/>
  </console>
  <channel type='unix'>
   <target type='virtio' name='org.qemu.guest_agent.0'/>
   <address type='virtio-serial' controller='0' bus='0' port='1'/>
  </channel>
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A pty serial console is set up on the VM, which enables rudimentary VM communication with the host. The console uses the UNIX channel on port 1. This is set up automatically and changing these settings is not recommended.

For more information about interacting with VMs, see Interacting with virtual machines by using the web console. 

  <input type='tablet' bus='usb'>
   <address type='usb' bus='0' port='1'/>
  </input>
  <input type='mouse' bus='ps2'/>
  <input type='keyboard' bus='ps2'/>
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The VM uses a virtual usb port, which is set up to receive tablet input, and a virtual ps2 port set up to receive mouse and keyboard input. This is set up automatically and changing these settings is not recommended. 

  <graphics type='vnc' port='-1' autoport='yes' listen='127.0.0.1'>
   <listen type='address' address='127.0.0.1'/>
  </graphics>
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The VM uses the vnc protocol for rendering its graphical output. 

  <redirdev bus='usb' type='tcp'>
   <source mode='connect' host='localhost' service='4000'/>
   <protocol type='raw'/>
  </redirdev>
  <memballoon model='virtio'>
   <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
  </memballoon>
 </devices>
</domain>
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The VM uses tcp re-director for attaching USB devices remotely, and memory ballooning is turned on. This is set up automatically and changing these settings is not recommended.

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