Cloud Computing

Since you're viewing this summary online, It is likely that you are familiar with the term "cloud computing", this is because cloud computing is now becoming widely used among many major companies that provides online services in different fields.
Examples of these companies are: "Amazon, Google, IBM, Sun, Cisco, Dell, HP, Intel, Novell, and Oracle". This means that the majority of the Internet users have probably used cloud computing services at some point of their lives.

So what exactly is cloud computing ?
It is a mean of storing your data and accessing various resources online, or precisely on a remote server instead of congesting your PC's hard drive with loads of documents, applications and images.
Cloud computing runs using servers and storage systems. A server is used to manage the traffic on the network using a set of protocols and a software called middleware to manage the system.

Types of clouds:

1- Public Cloud :
It can be accessed by any subscriber through the internet e.g.Google Drive.

2- Private Cloud :
It is owned by a specific organization or a group, where only the members of that group can access the cloud.

3- Community Cloud:
It is shared among multiple organizations that have the same cloud requirements.

4- Hybrid Cloud:
It is a combination of multiple clouds of any type of the latter clouds.

Cloud provider:
There are three types of cloud providers:
1- Software as a Service (SaaS):
Through SaaS, the subscriber has access to resources and applications. You won't have to save the software on your physical hard drive, and you will have access to the software from any of your devices.
However, SaaS gives its users the least control over the cloud.

2- Platform as a Service (PaaS):
It enables its subscribers to access the components they need to develop and run applications over the internet.

3- Infrastructure as a Service (IaaS):
This service provides its subscribers with access to the computational infrastructure. Giving the users more freedom in terms of storage and resources.

Overall, "subscribers gain more control over what they can do within the space of the cloud" as we go down the list.

Security:
When discussing cloud computing, peple are usually concerned of losing their privacy as it is very likely for a third party to have access to their personal documents and information.
However, the security of a user file on a cloud will be determined by several elements including:
The privacy policy set by the cloud provider, The user himself (business can negotiate for more trustworthy privacy policy than individuals), The security standards used by the provider, ..


references:
http://computer.howstuffworks.com/cloud-computing/cloud-computing1.htm
https://www.ibm.com/cloud-computing/what-is-cloud-computing
https://www.us-cert.gov/sites/default/files/publications/CloudComputingHuthCebula.pdf
https://www.unc.edu/courses/2010spring/law/357c/001/cloudcomputing/examples.html
http://me.pcmag.com/networking-communications-software-products/1758/feature/what-is-cloud-computing


Questions:
1- Is the data on a cloud still saved on a physical hard drive somewhere ?
2- If so, what is the maximum capacity that a cloud can withstand?
3- What is the possibility that a cloud break down ?