To Grasp the Cloud—Fundamental Concepts - Deploying and Managing a Cloud Infrastructure - page 51

implemented as a Type 1 (bare metal) or Type 2 (inside a host OS) hypervisor. There are a
host of open-source and proprietary hypervisors available for consumer and enterprise use
cases. Hypervisor technology enables the key features that define a cloud. These include
scalability, availability, shared resources, location, and hardware isolation. Applications
that run on the cloud are abstracted from the underlying physical hardware. This network
and application isolation enables agility for the applications and their ability to be distrib-
uted across a single data center or across physically separated data centers.
The four key elements that make up the foundation of the cloud are the physical infra-
structure, which is virtualized and offered as a service; the platform, which runs on top of
the virtualized hardware; applications, which run on top of the platform, and the enabling
services through which cloud resources are offered.
Chapter Essentials
Hypervisor A hypervisor is the technology that sits in between the physical hardware and
the OS. It virtualizes the compute, storage, and networking components. Hypervisors enable
multiple VMs to run on a single physical server and to be created, configured, and destroyed
through a centralized control panel. There are several open-source and proprietary hypervisor
products available.
Type 1 Hypervisor Type 1 or bare metal, hypervisors implement support for the hardware
they run on because they directly run on the bare hardware without the need for any host OS.
Type 2 Hypervisor These hypervisors need to be deployed on a host OS. Support for the
hardware on which they run is managed through the host OS on which the hypervisor is
installed. Both Type 1 and Type 2 hypervisors support running several guest OS instances.
Proprietary and Open-Source Hypervisors There are a host of open-source and proprietary
hypervisors available in the market. Some hypervisors started as an open-source project and
later became part of a commercial solution, such as, for example, the Xen Project, from which
came Citrix XenServer offerings.
Desktop Virtualization Desktop virtualization or a VDI enables workstations within an
enterprise to be virtualized inside a centralized data center and distribute resources based on
demand. A single OS image can be used to spin up multiple VMs. Individual workstations
connect to their respective VMs running inside the data center.
Infrastructure as a Service All the servers inside a data center, along with the networking
hardware that connects these servers, are completely virtualized and consolidated into a
single resource pool. This virtualized infrastructure is then offered as a service inside the
enterprise for applications to be deployed and delivered to end users or as a billable service
in the case of public cloud offerings.