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10.6. Hypervisor Requirements

Red Hat Virtualization Host (RHVH) has a number of hardware requirements and supported limits. The storage requirements for Red Hat Enterprise Linux hosts vary based on the amount of disk space used by their existing configuration but are expected to be greater than those of RHVH.

Table 10.4. Red Hat Virtualization Host Requirements and Supported Limits

Item Support Limit
A minimum of 1 physical CPU is required. Red Hat Virtualization supports the use of these CPU models in hosts:
  • AMD Opteron G1
  • AMD Opteron G2
  • AMD Opteron G3
  • AMD Opteron G4
  • AMD Opteron G5
  • Intel Conroe
  • Intel Penryn
  • Intel Nehalem
  • Intel Westmere
  • Intel Haswell
  • Intel SandyBridge Family
All CPUs must have support for the Intel® 64 or AMD64 CPU extensions, and the AMD-V™ or Intel VT® hardware virtualization extensions enabled. Support for the No eXecute flag (NX) is also required.
The amount of RAM required for each virtual machine varies depending on:
  • guest operating system requirements,
  • guest application requirements, and
  • memory activity and usage of virtual machines.
Additionally KVM is able to over-commit physical RAM for virtual machines. It does this by only allocating RAM for virtual machines as required and shifting underutilized virtual machines into swap.
See for the maximum and minimum supported RAM.
The minimum supported internal storage for a host is the total of the following list:
  • The root (/) partition requires at least 6 GB of storage.
  • The /boot partition requires at least 1 GB of storage.
  • The /var partition requires at least 15 GB of storage. For self-hosted engine deployment, this must be at least 60 GB.
  • The swap partition requires at least 8 MB of storage. The recommended size of the swap partition varies depending on both the system the host is being installed upon and the anticipated level of overcommit for the environment. See for more information.
Please note that these are the minimum storage requirements for host installation. It is recommended to use the default allocations which use more storage space.
PCI Devices
At least one network controller is required with a recommended minimum bandwidth of 1 Gbps.


When the Red Hat Virtualization Host boots a message may appear:
Virtualization hardware is unavailable.
(No virtualization hardware was detected on this system)
This warning indicates the virtualization extensions are either disabled or not present on your processor. Ensure that the CPU supports the listed extensions and they are enabled in the system BIOS.
To check that processor has virtualization extensions, and that they are enabled:
  • At the host boot screen press any key and select the Boot or Boot with serial console entry from the list. Press Tab to edit the kernel parameters for the selected option. After the last kernel parameter listed ensure there is a Space and append the rescue parameter.
  • Press Enter to boot into rescue mode.
  • At the prompt which appears, determine that your processor has the virtualization extensions and that they are enabled by running this command:
    # grep -E 'svm|vmx' /proc/cpuinfo
    If any output is shown, the processor is hardware virtualization capable. If no output is shown it is still possible that your processor supports hardware virtualization. In some circumstances manufacturers disable the virtualization extensions in the BIOS. Where you believe this to be the case consult the system's BIOS and the motherboard manual provided by the manufacturer.
  • As an additional check, verify that the kvm modules are loaded in the kernel:
    # lsmod | grep kvm
    If the output includes kvm_intel or kvm_amd then the kvm hardware virtualization modules are loaded and your system meets requirements.