An additional aspect of most Cloud Computing discussions that I have had is what the difference and purpose of types of clouds. You may be saying "I thought this was discussed in the previous blog entry Cloud Computing Explained ?" This however, is not the case as we are not referring to types of Cloud Computing, but types of Clouds themselves. This subtle difference in wording changes the topic a great deal. Types of Cloud actually refers to the Cloud Architectures themselves, not the things are being offered by or on the Cloud (Although the offerings are dependent on the Architectures).
To make a bit more sense of this here is a diagram:
This diagram shows different TYPES of Cloud Computing (This is what was discussed in the Cloud Computing Explained post)
Types of Clouds
Below is a diagram showing the Types of Clouds (Notice the difference between Types of Computing vs Types of Clouds):
The three primary Types of Clouds are:
Private - This is a Cloud that is isolated from outside access either logically or physically (logically being through virtualization and VPN) or physically by being located only at a physical datacenter
Public - This is a Shared Cloud that is accessible by anyone, the only separation is via credentials and commonly the underlying infrastructure is shared by many or all users. The separation is usually purely logical.
Hybrid - A Hybrid Cloud is somewhere between that of a Public and Private Cloud. A Hybrid Cloud uses resources the majority of the time in either the Private Cloud (The Most Common Configuration) or the Public Cloud (Less Common), then when specific needs arise, thresholds are met, alarms are triggered, etc. resources are brought online in the other cloud to meet demands. The most common scenario is a bursting even where a company leverages an External Provider (Public Cloud) for utilization when they are temporarily over capacity. An example would be an online retailer that for two months out of the years has an extreme demand placed on its web servers. This demand is outside the normal capabilities of their infrastructure, yet it doesn't make sense to buy additional hardware to service a need that is short and temporary. This is an ideal scenario for Hybrid Cloud usage.
What is interesting about this is that the Cloud Architecture that is used can be different even if the Type of Cloud Computing Service provided is the same.
Above is a diagram of how a small subset of Cloud Computing Types can fall into one or more Types of Clouds.
Integration between Clouds
Below is a diagram showing the most common way of integration between Public and Private Clouds at the Hybrid Junction Point.
The key integration is in the Hybrid Layer where an API and/or VPN is leveraged to coordinate resources between the Internal Cloud/Private Cloud and the Public/(SaaS/PaaS/IaaS). This allows for automation and security when the two types of resources are co-mingled. As the Cloud Computing Trend continues to evolve, there are other possible uses for all three different types of scenarios that become more and more interesting.
Amazon,
Cloud,
Cloud Computing,
Gigaspaces,
Google,
IaaS,
Microsoft,
Netsuite,
PaaS,
Rackspace,
Rightscale,
SaaS,
Salesforce.com,
VMware,
XaaS