Chapter 3. Requirements and limitations of Red Hat Enterprise Virtualization Hypervisors
3.1. System requirements
- A CPU with the hardware virtualization extensions; either an AMD system with AMD-V™ or an Intel system with Intel VT®.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.
ImportantSome systems have the virtualization extensions disabled in BIOS; virtualization extensions must be enabled in BIOS. First, boot into rescue mode (by typing
linux rescueat the RHEV Hypervisor boot prompt) or by entering the shell from the configuration menu. Determine whether your processor has virtualization extensions with this command:
$ grep -E 'svm|vmx' /proc/cpuinfoIf any output is shown, the processor is hardware virtualization capable. However in some circumstances manufacturers disable the virtualization extensions in BIOS. As an additional check, verify that the
kvmmodules are loaded in the kernel:
# lsmod | grep kvmIf the output includes
kvmhardware virtualization modules are loaded and your system meets requirements.
- An Intel® 64 or AMD64 CPU extension.
- At least one network controller with a minimum bandwidth of 1Gbps.
- At least 512MB of RAM.
- Sufficient RAM for guest virtual machines. The amount of RAM required for virtual machines depends on:
KVM can overcommit physical RAM for virtual machines by only allocating RAM for virtual machines as required, and shifting under-utilized virtual machines into swap.
- the guest operating system's requirements,
- the virtual machine's application requirements, and
- memory activity and usage of the virtual machine.
- The minimum supported internal storage for a Hypervisor is the total of the following list:
- The root partitions require exactly 512MB of storage.
- The boot partition requires exactly 50MB of storage.
- The logging partition is required and the recommended size is 2048MB.
- The default and minimum size for the configuration partition is 5MB.
- Swap is required and the recommended size is the recommended swap partition (from this article on Red Hat Knowledgebase) and the overcommit ratio multiplied by the RAM (the default overcommit ratio is 0.5). The minimum size for the swap partition is 5 MB.
Recommended swap + (RAM * overcommit) = swap partition size
- The default size of the data partition is the size of the system's RAM plus 512MB. The minimum size is 256MB.
Example 3.1. Determining minimum storage requirements
The root partitions = 512MB The boot partition = 50MB The logging partition = 2048MB The config partition = 5MB The swap partition (using a 0.6 overcommit ratio) 4GB (4096MB) + (0.6 * 14GB) = 12698MB The data partition is the size of the system's RAM plus 512MB (14GB + 512MB) = 14750MB ------------------------------------------------------------- Total = 30063MB