Comparison of 3 Main Cloud Computing Deployment Models

Matrix	Private Cloud	Public Cloud	Hybrid Cloud
Security	Most Secure as everything is on –premise	Good but depend on the security measures considered by cloud service provider	Very secure, integration capabilities add another layer of security
Reliability	High, as everything on premise	Medium, Depend on the Internet connectivity speed and cloud service provider availability	Medium to high as frequently accessed items are kept on premise but also depends on Internet connection speed
Cost	Very high, as enterprise need to invest in data center, cooling systems, electricity, etc.	Low, as follows Pay-per-use model	Moderate, as allows to consume some resources from public cloud based on pay-per-use
Performance	Very Good	Medium	Good, as supports caching of frequently accessed items
Deployment Premise	On Enterprise premise who want to use it	On Cloud Service Provider’s Data Centers and App Servers	Partially on enterprise premise and partial on third party public cloud
Customer Coverage	Single customer specific	Can be used by multiple customer at a time	Multi customer support but still depend on the context of use case
Access Level	Private	Public	Partially private and partially public
Maintenance	High as everything on premise	No maintenance	Required only for the resources which are on premise
Flexibility	Low	Very High	High
Examples	Government agencies and research labs like NASA, etc.	Google, Salesforce.com clouds, etc.	GoGrid hybrid cloud installations, etc.