Cloud computing is an emerging technology that can allow user’s large amount of data to store in cloud and it can be access from anywhere. It provides various kinds of services to users such as Software as a service, Infrastructure as a service, and Platform as a service etc. It can manage to provide cost effective, easy to manage, elastic, and powerful resources over the Internet. It uses optimal and shared utilization to enhance the ability of the hardware resources .These features help user and organizations to switch their applications and services to the cloud. There are two important aspects of cloud storage-(1) Data integrity is an important aspect while attain validation, violation and correctness of data on cloud storage. Data integrity checking mechanism plays a major role in Cloud Computing. This deals with checking the integrity of data at remote cloud storage server. It ensures that data at the sender and receiver side are same. User can detect data integrity violations with the help of this mechanism while retrieving from remote cloud storage server. It refers to the completeness, accuracy and consistency of data over its entire life cycle. This can be determined by the absence of alteration between two instances of data.(2)- Data compression is a process of eliminating redundancies in order to reduce storage space and cost on cloud storage .It implies sending & storing smaller number of bits. It involves manipulating and modifying bits structure of data in such a way that it reduce size. This paper propose a new methodology to improve the performance of data integrity checking and to optimize the compression ratio.

Data integrity checking Auditing Mechanism