Chapter 2. System Requirements

This chapter lists system requirements for successfully running virtual machines, referred to as VMs on Red Hat Enterprise Linux 6. Virtualization is available for Red Hat Enterprise Linux 6 on the Intel 64 and AMD64 architecture.
The KVM hypervisor is provided with Red Hat Enterprise Linux 6.
For information on installing the virtualization packages, see Chapter 5, Installing the Virtualization Packages.

Minimum system requirements

  • 6 GB free disk space.
  • 2 GB of RAM.

Recommended system requirements

  • One processor core or hyper-thread for the maximum number of virtualized CPUs in a guest virtual machine and one for the host.
  • 2 GB of RAM plus additional RAM for virtual machines.
  • 6 GB disk space for the host, plus the required disk space for each virtual machine.
    Most guest operating systems will require at least 6GB of disk space, but the additional storage space required for each guest depends on its image format.
    For guest virtual machines using raw images, the guest's total required space (total for raw format) is equal to or greater than the sum of the space required by the guest's raw image files (images), the 6GB space required by the host operating system (host), and the swap space that guest will require (swap).

    Equation 2.1. Calculating required space for guest virtual machines using raw images

    total for raw format = images + host + swap
    For qcow images, you must also calculate the expected maximum storage requirements of the guest (total for qcow format), as qcow and qcow2 images grow as required. To allow for this expansion, first multiply the expected maximum storage requirements of the guest (expected maximum guest storage) by 1.01, and add to this the space required by the host (host), and the necessary swap space (swap).

    Equation 2.2. Calculating required space for guest virtual machines using qcow images

    total for qcow format = (expected maximum guest storage * 1.01) + host + swap
Guest virtual machine requirements are further outlined in the Red Hat Enterprise Linux 6 Virtualization Administration Guide in Chapter 6. Overcommitting with KVM.
Calculating Swap Space

Using swap space can provide additional memory beyond the available physical memory. The swap partition is used for swapping underused memory to the hard drive to speed up memory performance. The default size of the swap partition is calculated from the physical RAM of the host.

Red Hat Knowledgebase contains an article on safely and efficiently determining an appropriate size for the swap partition, available here:
KVM Requirements

The KVM hypervisor requires:

  • an Intel processor with the Intel VT-x and Intel 64 extensions for x86-based systems, or
  • an AMD processor with the AMD-V and the AMD64 extensions.
Refer to the Red Hat Enterprise Linux 6 Virtualization Administration Guide to determine if your processor has the virtualization extensions.
Storage Support

The guest virtual machine storage methods are:

  • files on local storage,
  • physical disk partitions,
  • locally connected physical LUNs,
  • LVM partitions,
  • NFS shared file systems,
  • iSCSI,
  • GFS2 clustered file systems,
  • Fibre Channel-based LUNs, and
  • Fibre Channel over Ethernet (FCoE).