The data in cloud is stored in a physical computer or server. The building where this server is located is called a Data Center.

At first a company search for a place or in cloud term region to set up a data center. In a data center the power supply is a major component. That's

why a company creates multiple data center in the same region. In a data center there are mainly 2 floors. Each multiple servers with the same configuration with ome server in 1stb floor is configured to another server in another floor. First a cloud architect ask a client that how important their application is. if client says its need ts to be run all the time then they will say ok we will map 2 servers in the same data data center to you. If the first server has suddently any hardware issue then it will automatically move to the other server. The adta will be copied, the configuration will be copied automatically. This is called Fault Domain.

Now if its a power supply failure then the whole building will be affected. So That's why a company creates multiple data center in the same region. If one building is affected then that client machine is moved to another server in another data center. This is called Availability Domain. A client can choose a availability domain and a fault domain based on their requirement and will pay according to it.

Now ifs the whole region is affected then both data centers will be affected. So they will also create a data center in another region in the same country.

Now in an application like amazon there is 3 layers. Frontend layer, Bussiness layer, Database layer. If the distance between these layers is too much then the communication time will be more. For amazon they more than 1 billion customer base so these small time will increase to more. So amazon will make its data center in India if they have a customer base in India rather than making it in US.

In a cloud server there are compartment. Compartments are like a partition in a flat. In a flat there are several rooms. We can give one person access to one room. In a server its similar. We can give access to one compartment to one user.

To create a cloud server we have to give one name, choose its configuration like choosing its OS, Network etc. Then down load both public key and private key. A public key is like the lock and private key is like the key. Public key will remain in the server and private key will be with the user which will be used in ssh (secure shell).