VIRTUALIZATION
Virtualization, in computing, refers to
the act of creating a virtual version of something, including but not limited
to a virtual computer hardware platform, operating system,storage device, or
computer network resources.
Virtualization
began in 1960s mainframe computers as a method of logically dividing the system
resources provided by mainframes between different applications. Since then,
the meaning of the term has broadened.
HARDWARE VIRTUALIZATION
Hardware virtualization of platform
virtualization refers to the creation of a virtual machine that acts like a
real computer with an operating system. Software executed on these virtual
machines is separated from the underlying hardware resources. For example, a
computer that is running Microsoft windows may host a virtual machine that
looks like a computer with the ubuntu linux operating system, ubuntu based
software can be run on the virtual machine.
SNAPSHOTS
A snapshot is the state of a virtual
machine, and generally its storage devices, at an exact point in time. A
snapshot enables the virtual machine’s state at the time of the snapshot to e
restored later, effectively undoing any changes that occurred afterwards. This
capability is useful as a backup technique, for example, pri
or to performing a risky operation.
MIGRATION
The snapshots described above can be moved
to another host machine with its own hypervisor, when the VM is temporarily
stopped, snapshotted, moved, and the resumed on the new host, this is known as
migration. If the older snapshots are kept in sync regularly, this operation
can be quite fast, and allow the VM to provide uninterrupted service while its
prior physical host is for example, taken down for physical maintenance.
FAILOVER
Similar to teleportation above, failover
allows the VM to continue operations if the host fails. However, in this case,
the VM continues operation from the last-known coherent state, rather than the
current state, based on whatever materials the backup server was last provided
with.
