The hypervisor is a virtual machine monitor (VMM) that manages resources for virtual machines. The name hypervisor is suggested as it is a supervisory tool for the virtual machines. There are mainly two types of hypervisors :

- Type-1: the guest Vm runs directly over the host hardware, e.g Xen, Hyper-V, VmWare ESXi

- Type-2: the guest Vm runs over hardware through a host OS, e.g Kvm, Oracle virtualbox

Cloud computing architecture consists of many layers which help it to be more organized and can be managed from one place. The layers are as follows:

1. Cloud controller or CLC is the top most level in the hirerachy which is used to manage the virtualized resources like servers, network and storage with the user APIs. 

2. Walrus is used for the storage and act as a storage controller to manage the demands of the users. It maintains a scalable approach to control the virtual machine images and user data.

3. Cluster Controller or CC is used to control all the virtual machines for executions the virtual machines are stored on the nodes and manages the virtual networking between Virtual machines and external users.

4. Storage Controller or SC provides a storage area in block form that are dynamically attached by Virtual machines. 

5. Node Controller or NC is at the lowest level and provides the functionality of a hypervisor that controls the VMs activities, which includes execution, management and termination of many instances.

Eucalyptus stands for “Elastic Utility Computing Architecture for Linking Your Programs to Useful Systems” and provides an open source software infrastructure to implement clusters in cloud computing platform. It is used to build private, public and hybrid clouds. It can also produce your own datacenter into a private cloud and allow you to extend the functionality to many other organizations. Eucalyptus provides APIs to be used with the web services to cope up with the demand of resources used in the private clouds.

Cloud computing platform has various databases that are in support. The open source databases that are developed to support it is as follows:

- MongoDB: is an open source database system which is schema free and document oriented database. It is written in C++ and provides tables and high storage space. 

- CouchDB: is an open source database system based on Apache server and used to store the data efficiently

- LucidDB: is the database made in Java/C++ for data warehousing. It provides features and functionalities to maintain data warehouse.

The security laws which are implements to secure data in the cloud are as follows:

- Input validation : controls the input data which is being to any system.

- Processing  : control that the data is being processed correctly and completely in an application.

- File : control the data being manipulated in any type of file.

- Output reconciliation : control the data that has to be reconciled from input to output.

- Backup and recovery: control the security breaches logs and the problems which has occurred while creating the back.

Cloud computing is going all together for a different look as it now includes different data types like emails, contracts, images, blogs, etc. The amount of data increasing day by day and cloud computing is requiring new and efficient data types to store them. For example if you want to save video then you need a data type to save that. Latency requirements are increasing as the demand is increasing. Companies are going for lower latency for many applications.

Cloud data center doesn’t require experts to operate it, but it requires skilled people to see the maintenance, maintain the workloads and to keep the track of the traffic. The labor cost is 6% of the total cost to operate the cloud data center. Power distribution and cooling of the datacenter cost 20% of the total cost. Computing cost is at the end and is the highest as it is where lots of resources and installation has to be done. It costs the maximum left percentage.

Security is one of the major aspects which come with any application and service used by the user. Companies or organizations remain much more concerned with the security provided with the cloud. There are many levels of security which has to be provided within cloud environment such as:

• Identity management: it authorizes the application service or hardware component to be used by authorized users.

• Access control: permissions has to be provided to the users so that they can control the access of other users who are entering the in the cloud environment.

• Authorization and authentication: provision should be made to allow the authorized and authenticated people only to access and change the applications and data.