Cloud Computing

1. What is Cloud Computing?

Cloud computing is an on-demand availability of computer system resources like data storage and computing power without active management by the user.

2. Why Cloud Computing?

There are following benefits of Cloud computing: 

• Scalibility - Scale up (Add) and Scale down (remove) resources in response to demand. Two methods of scaling:
  - Virtual Scaling - Adding additional capacity to existing resources. e.g. Adding processing power to a server.
  - Horizontal Scaling - Adding duplicate resources. e.g. virtual machines
• Reliability - Avoid outages and recover from disaster e.g. Improve availability by adding load balancer and improve recoverablity by backup and restore.
• Efficiency - Only Pay for what is needed and avoid unnessary expenses. e.g. efficient resource utilization and avoid over licensing etc.
• Advanced Security 
• Mobility - An environment is accessible from anywhere in the world

Example: An ecommerce web portal can scale up their resources in response to demand during holiday season and avoid an outage due to high volume. 

3. Major Players in the Cloud Computing and their market Share:

4. Type of Cloud 

1. Private Cloud
   • The server owned by and dedicated to only one tenant (user)
   • The servers can be on-premises or off-premises
   • The owner is responsible for the managment and maintaenance of the servers and for planning for future capacity
   • Fully customizable 
   • Fully Private network 
   • High IT overhead
2. Public Cloud 
   • The services are shared between multiple tenants (users). 
   • The servers will be off premises 
   • Limited customizations 
   • Shared network
   • Scalable with demand 
   • Low IT overhead
3. Hybrid Cloud 
   • Uses a mix of on-premises, private and public cloud services by allowing data and application to be shared between them. 

5. Cloud Services

1. SaaS
   • Software as a service
   • Fully functional applications provided e.g. SalesForce, Planview, JIRA, Rally, Gmail etc.
   • Operating system is irrelevent 
2. PaaS
   • Plateform as a service
   • Operating system included. e.g. Windows, Linux etc. 
3. IaaS
   1. Infrastructure as a service
   2. Virtual Machines on which required operating system and environment and application are deployed
   3. Inclues storage as a service