Selecting a Service Platform - The Practice of Cloud System Administration - page 65

so economically. However, a large company can achieve similar economies of
scale by building a large infrastructure that is shared by many in-house customers.
Because it is in-house, it is private—a criterion often required by industries that are
highly regulated.
• Contract for an On-Premises, Externally Run Service: Some companies will
run an in-house cloud service for you. They differ in how much control and cus-
tomization they provide. You benefit from their expertise and mitigate privacy is-
sues by owning and controlling the equipment.
• Maximize Hardware Output: Pursue a strategy of squeezing every bit of pro-
ductivity and efficiency out of computers by eschewing virtualization. When an in-
frastructure has hundreds of thousands of computers or millions of cores, improv-
ing efficiency by 1 percent can be the equivalent of gaining thousands of new com-
puters. The loss of efficiency from virtualization can be a huge expense. In this
strategy physical machines, rather than virtual machines, are used and services are
tightly packed on them to maximize utilization.
• Implement a Bare Metal Cloud: Manage physical machine infrastructure like a
virtual machine cloud. Provide physical machines via the same API used for provi-
sioning virtual machines. The benefits of being able to spin up virtual machines
can be applied to physical machines with some planning. Rather than selecting the
exact custom configuration needed for each physical machine, some companies
opt to purchase hundreds or thousands of machines all configured the same way
and manage them as a pool that can be reserved by departments or individuals.
They do this by providing an API for allocating machines, wiping and reinstalling
their OS, rebooting them, controlling access, and returning them to the pool. The
allocations may not be as fast or as dynamic as virtual machines, but many of the
same benefits can be achieved.
3.6 Summary
This chapter examined a number of platforms. Infrastructure as a Service (IaaS) provides
a physical or virtual machine for your OS and application installs. Platform as a Service
(PaaS) provides the OS and application stack or framework for you. Software as a Service
(SaaS) is a web-based application.
You can create your own cloud with physical or virtual servers, hosting them yourself
or using an IaaS provider for the machines. Your specific business needs will guide you in
determining the best course of action for your organization.