⁠1.3. Hypervisor Requirements

1.3.1. Virtualization Host Hardware Requirements Overview
1.3.2. Virtualization Host CPU Requirements
1.3.3. Virtualization Host RAM Requirements
1.3.4. Virtualization Host Storage Requirements
1.3.5. Virtualization Host PCI Device Requirements

⁠1.3.1. Virtualization Host Hardware Requirements Overview

Red Hat Enterprise Virtualization Hypervisors and Red Hat Enterprise Linux Hosts have a number of hardware requirements and supported limits.

⁠1.3.2. Virtualization Host CPU Requirements

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 Sandybridge
  • Intel Haswell
  • IBM POWER8
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. To check that your processor supports the required flags, and that they are enabled:
  1. At the Red Hat Enterprise Linux or Red Hat Enterprise Virtualization Hypervisor boot screen, press any key and select the Boot or Boot with serial console entry from the list.
  2. Press Tab to edit the kernel parameters for the selected option.
  3. Ensure there is a Space after the last kernel parameter listed, and append the rescue parameter.
  4. Press Enter to boot into rescue mode.
  5. At the prompt which appears, determine that your processor has the required extensions and that they are enabled by running this command: 
    # grep -E 'svm|vmx' /proc/cpuinfo | grep nx
    If any output is shown, then the processor is hardware virtualization capable. If no output is shown, then it is still possible that your processor supports hardware virtualization. In some circumstances manufacturers disable the virtualization extensions in the BIOS. If you believe this to be the case, consult the system's BIOS and the motherboard manual provided by the manufacturer.

Note

You must enable Virtualization in the BIOS. Cold boot the host after this change to ensure that the change is applied.

⁠1.3.3. Virtualization Host RAM Requirements

It is recommended that virtualization hosts have at least 2 GB of RAM. The amount of RAM required varies depending on the following factors:
  • Guest operating system requirements.
  • Guest application requirements.
  • Memory activity and usage of guests.
The fact that KVM is able to overcommit physical RAM for virtualized guests must also be taken into account. This allows for provisioning of guests with RAM requirements greater than what is physically present, on the basis that the guests are not all concurrently at peak load. KVM does this by only allocating RAM for guests as required and shifting underutilized guests into swap.
A maximum of 2 TB of RAM per virtualization host is currently supported.

⁠1.3.4. Virtualization Host Storage Requirements

Virtualization hosts require local storage to store configuration, logs, kernel dumps, and for use as swap space. The minimum storage requirements of the Red Hat Enterprise Virtualization Hypervisor are documented in this section. 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 the Red Hat Enterprise Virtualization Hypervisor.
For Red Hat Enterprise Virtualization Hypervisor requirements, see the following table for the minimum supported internal storage for each version of the Hypervisor:
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Table 1.2. Red Hat Enterprise Virtualization Hypervisor Minimum Storage Requirements

Version Root Partition Configuration Partition Logging Partition Data Partition Swap Partition Minimum Total
Red Hat Enterprise Virtualization Hypervisor 6 512 MB 8 MB 2048 MB 512 MB 8 MB 3.5 GB
Red Hat Enterprise Virtualization Hypervisor 7 9 GB 8 MB 2048 MB 512 MB 8 MB 12 GB
The logging partition requires a minimum of 2048 MB storage. However, it is recommended to allocate more storage to the logging partition if resources permit.
The data partition requires a minimum of 512 MB storage. The recommended size is at least 1.5 times as large as the RAM on the host system plus an additional 512 MB. 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 guests 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.
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Example 1.1. Calculating Swap Partition Size

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

Important

By default the Red Hat Enterprise Virtualization Hypervisor defines a swap partition sized using the recommended formula. An overcommit ratio of 0.5 is used for this calculation. For some systems the result of this calculation may be a swap partition that requires more free disk space than is available at installation. Where this is the case Hypervisor installation will fail.
If you encounter this issue, manually set the sizes for the Hypervisor disk partitions using the storage_vol boot parameter.
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Example 1.2. Manually Setting Swap Partition Size

In this example the storage_vol boot parameter is used to set a swap partition size of 4096 MB. Note that no sizes are specified for the other partitions, allowing the Hypervisor to use the default sizes. 
storage_vol=:4096::::

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.

⁠1.3.5. Virtualization Host PCI Device Requirements

Virtualization hosts must have at least one network interface with a minimum bandwidth of 1 Gbps. It is recommended that each virtualization host have two network interfaces with one dedicated to support network intensive activities such as virtual machine migration. The performance of such operations are limited by the bandwidth available.