What is Private Cloud?
Private Cloud has generally been mainly used by large enterprise customers. This is an internally hosted Cloud service which is very secure. Large companies have been using it as a continualization of their previous virtualization efforts. Private Cloud is most often defined by companies that want their file backup to be in house or their software to be hosted on site.
Private Cloud is generally used by larger enterprises because of the requirement of IT expertise in house. Many smaller companies cannot afford to staff the IT department needed to run on a private cloud.
What is Public Cloud?
Public Cloud is the ability of companies to have their files backed up in externally hosted data centers. Public Cloud will back up and handle a number of different platforms and many enterprises have been effectively using private Cloud for many years.
This is particularly useful for small companies who have been using email as a file storage system. Switching to public Cloud will allow them to easily store their information off site.
However, many large enterprises don't want to explore the avenue of public Cloud because it takes the control of security out of their hands. They need to fully trust their hosting provider to handle all security measures. And while the data is encrypted, many companies feel more comfortable knowing that it is being watched over by their team of IT professionals.
According to a Redmond Channel Partner Webcast entitled "How Cloud Services Help Your Bottom Line," small and large companies alike are projecting a 30% spending increase for public IT Cloud services in 2011.