Over the past few years, we have seen a gradual transition from traditional computer centers with dedicated resources to virtual machines and cloud computing.
During this time, people have realized some of the value of virtualization in terms of savings and resource optimization. Unfortunately there are still a number of warts in virtualization that have followed the migration to the cloud.
Before we discuss those warts, it is important to fully describe the cloud environment about which we are talking.
While most people want to talk about software-as-a-service (SaaS) and platform-as-a-service (PaaS) – and we could include them in our conversation – we really want to talk about clouds that are transparent and migratory.
These clouds are typically described as public, private or hybrid.
What is a private cloud?
A private cloud is (typically) a cloud created within a corporation (only using corporate-owned machines) and is entirely at the control of the corporation. The cloud includes numerous computers and can extend among different computer facilities, as well as crossing geographical boundaries.
What is a public cloud?
A public cloud is controlled by someone other than the corporation and can have multiple entities participating all on the same machine. Each entity can have its own separate virtual machine (VM) and may not readily be able to see other entities. The cloud location and co-residents are unknown.
What is a hybrid cloud?
A hybrid cloud consists of some resources being controlled by the corporation and some by an outside entity. There may or may not be a bleed-over of clouds from the private cloud to the public cloud.