Red Hat ENTERPRISE LINUX 5 - VIRTUALIZATION GUIDE Manual page 390

Glossary
I/O
Itanium®
Kernel SamePage Merging
Kernel-based Virtual
Machine
LUN
MAC Addresses
Migration
376
Short for input/output (pronounced "eye-oh"). The term I/O describes
any program, operation or device that transfers data to or from a
computer and to or from a peripheral device. Every transfer is an
output from one device and an input into another. Devices such as
keyboards and mouses are input-only devices while devices such as
printers are output-only. A writable CD-ROM is both an input and an
output device.
The Intel Itanium® processor architecture.
The Kernel SamePage Merging (KSM) module is used by the KVM
hypervisor to allow KVM guests to share identical memory pages.
The pages shared are usually common libraries or other identical,
high-use data. KSM can increase the performance of certain guests
by keeping these libraries in cache for various guests as well as
increasing guest density.
KVM (Kernel-based Virtual Machine) is a
Linux on AMD64 and Intel 64 hardware. VM is a Linux kernel module
built for the standard Red Hat Enterprise Linux kernel. KVM can run
multiple, unmodified virtualized guest Windows and Linux operating
systems. KVM is a hypervisor which uses the libvirt virtualization tools
(virt-manager and virsh).
KVM is a set of Linux kernel modules which manage devices,
memory and management APIs for the Hypervisor module itself.
Virtualized guests are run as Linux processes and threads which are
controlled by these modules.
A Logical Unit Number (LUN) is a number assigned to a logical unit (a
SCSI protocol entity).
The Media Access Control Address is the hardware address for a
Network Interface Controller. In the context of virtualization MAC
addresses must be generated for virtual network interfaces with each
MAC on your local domain being unique.
Migration is name for the process of moving a virtualized guest from
one host to another. Migration can be conducted offline (where the
guest is suspended and then moved) or live (where a guest is moved
without suspending). Xen fully virtualized guests, Xen para-virtualized
guest and KVM fully virtualized guests can all be migrated.
Migration is a key feature of virtualization as software is completely
separated from hardware. Migration is useful for:
• Load balancing - guests can be moved to hosts with lower usage
when a host becomes overloaded.
• Hardware failover - when hardware devices on the host start to fail,
guests can be safely relocated so the host can be powered down
and repaired.
Full virtualization
solution for