Introduction to the HP Virtual Server Environment

Integrity Virtual Machines
Another solution in HP’s partitioning continuum is called HP Integrity Virtual Machines. This is a fully
virtualized environment for running applications. Figure 4 illustrates how Integrity Virtual Machines
are architected. The VM Host runs on any HP Integrity system or nPartition, which means that you do
not need a cell-based system to use Integrity Virtual Machines. On top of the VM Host you run virtual
machines, which present themselves to the VM Host as physical servers. When an OS is installed on
a virtual machine, the virtual machine becomes a guest. In an Integrity Virtual Machines environment,
all of the resources in a guest are virtualized. The physical CPUs, memory, and I/O devices are
managed by the VM Host. What the OS inside the virtual machine sees is a virtual resource that is
mapped on top of the physical devices in the system. This allows the physical resources to be shared
by multiple guests.
The virtualization that is provided by Integrity Virtual Machines is so complete that the operating
systems running inside the virtual machines run without modification. This means that the same
Integrity version of each OS (HP-UX, Windows, and Linux) that runs on a standalone system or
nPartition will run on a virtual machine.
Because of this level of isolation, software running inside a virtual machine cannot determine that it is
not running on a physical system. All of the resources that are presented are virtual, and the virtual
machine might be sharing those resources with multiple other virtual machines. As a result, the
resource allocation to virtual machines is very dynamic by default, but is generally transparent to
applications running inside the virtual machine.
Integrity Virtual Machines utilize Accelerated Virtual I/O (AVIO) drivers for networks and/or storage.
These VM-aware drivers streamline the I/O path and related performance of Integrity Virtual
Machines.
HP also provides a capability called Integrity Online VM Migration. Integrity Online VM Migration
enables an Integrity virtual machine, its guest O/S and its applications to be dynamically moved from
one VM Host to another without service disruption. No shutdown or reboot is required. All I/O
connections to networks and storage remain active throughout the migration. This capability is
particularly helpful for proactive maintenance and workload balancing.
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