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10.6. Hypervisor Requirements

Red Hat Enterprise Virtualization Hypervisors have a number of hardware requirements and supported limits.
Table 10.4. Red Hat Enterprise Virtualization Hypervisor Requirements and Supported Limits
Item Support Limit
CPU
  • A minimum of 1 physical CPU is required. Red Hat Enterprise Virtualization supports the use of these CPU models in virtualization 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
    • IBM POWER 8
    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.
RAM
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 https://access.redhat.com/articles/rhel-limits for the maximum and minimum supported RAM.
Storage
The minimum supported internal storage for a Hypervisor is the total of the following list:
  • The root partitions require at least 512 MB of storage.
  • The configuration partition requires at least 8 MB of storage.
  • The recommended minimum size of the logging partition is 2048 MB.
  • The data partition requires at least 256 MB of storage. Use of a smaller data partition may prevent future upgrades of the Hypervisor from the Red Hat Enterprise Virtualization Manager. By default all disk space remaining after allocation of swap space will be allocated to the data partition.
  • The swap partition requires at least 8 MB of storage. The recommended size of the swap partition varies depending on both the system the Hypervisor is being installed upon and the anticipated level of overcommit for the environment. Overcommit allows the Red Hat Enterprise Virtualization environment to present more RAM to virtual machines than is actually physically present. The default overcommit ratio is 0.5.
    The recommended size of the swap partition can be determined by:
    • Multiplying the amount of system RAM by the expected overcommit ratio, and adding
    • 2 GB of swap space for systems with 4 GB of RAM or less, or
    • 4 GB of swap space for systems with between 4 GB and 16 GB of RAM, or
    • 8 GB of swap space for systems with between 16 GB and 64 GB of RAM, or
    • 16 GB of swap space for systems with between 64 GB and 256 GB of RAM.
    For a system with 8 GB of RAM this means the formula for determining the amount of swap space to allocate is: 
    (8 GB x 0.5) + 4 GB = 8 GB
Please note that these are the minimum storage requirements for Hypervisor 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.

Important

When the Red Hat Enterprise Virtualization Hypervisor 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 Hypervisor 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.

Important

The Red Hat Enterprise Virtualization Hypervisor does not support installation on fakeraid devices. Where a fakeraid device is present it must be reconfigured such that it no longer runs in RAID mode.
  1. Access the RAID controller's BIOS and remove all logical drives from it.
  2. Change controller mode to be non-RAID. This may be referred to as compatibility or JBOD mode.
Access the manufacturer provided documentation for further information related to the specific device in use.
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