Chapter 1. Introducing virtualization in RHEL

Next steps

• To start using virtualization in Red Hat Enterprise Linux 9, see Enabling virtualization in Red Hat Enterprise Linux 9.
• In addition to Red Hat Enterprise Linux 9 virtualization, Red Hat offers a number of specialized virtualization solutions, each with a different user focus and features. For more information, see Red Hat virtualization solutions.

• Flexible and fine-grained allocation of resources

  A VM runs on a host machine, which is usually physical, and physical hardware can also be assigned for the guest OS to use. However, the allocation of physical resources to the VM is done on the software level, and is therefore very flexible. A VM uses a configurable fraction of the host memory, CPUs, or storage space, and that configuration can specify very fine-grained resource requests.

  For example, what the guest OS sees as its disk can be represented as a file on the host file system, and the size of that disk is less constrained than the available sizes for physical disks.

• Software-controlled configurations

  The entire configuration of a VM is saved as data on the host, and is under software control. Therefore, a VM can easily be created, removed, cloned, migrated, operated remotely, or connected to remote storage.

• Separation from the host

  A guest OS runs on a virtualized kernel, separate from the host OS. This means that any OS can be installed on a VM, and even if the guest OS becomes unstable or is compromised, the host is not affected in any way.

• Space and cost efficiency

  A single physical machine can host a large number of VMs. Therefore, it avoids the need for multiple physical machines to do the same tasks, and thus lowers the space, power, and maintenance requirements associated with physical hardware.

• Software compatibility

  Because a VM can use a different OS than its host, virtualization makes it possible to run applications that were not originally released for your host OS. For example, using a RHEL 7 guest OS, you can run applications released for RHEL 7 on a RHEL 9 host system.

  Note

  Not all operating systems are supported as a guest OS in a RHEL 9 host. For details, see Recommended features in RHEL 9 virtualization.

• Metadata such as the name of the VM, time zone, and other information about the VM.
• A description of the devices in the VM, including virtual CPUs (vCPUS), storage devices, input/output devices, network interface cards, and other hardware, real and virtual.
• VM settings such as the maximum amount of memory it can use, restart settings, and other settings about the behavior of the VM.

• virsh - A versatile virtualization command-line utility and shell with a great variety of purposes, depending on the provided arguments. For example:

  • Starting and shutting down a VM - virsh start and virsh shutdown
  • Listing available VMs - virsh list
  • Creating a VM from a configuration file - virsh create
  • Entering a virtualization shell - virsh

  For more information, see the virsh(1) man page on your system.

• virt-install - A CLI utility for creating new VMs. For more information, see the virt-install(1) man page on your system.
• virt-xml - A utility for editing the configuration of a VM.
• guestfish - A utility for examining and modifying VM disk images. For more information, see the guestfish(1) man page on your system.

• The RHEL 9 web console, also known as Cockpit, provides a remotely accessible and easy to use graphical user interface for managing VMs and virtualization hosts.

  For instructions on basic virtualization management with the web console, see Managing virtual machines in the web console.