Applying Erasure Codes for Fault Tolerance in Cloud-RAID

Public cloud storage services enable organizations to manage data with low operational expenses. However, the benefits come along with challenges and open issues such as security and reliability. In our work, we presented a system that improves availability, confidentiality and reliability of data stored in the cloud. To achieve this objective, we encrypt user´s data and make use of erasure codes to stripe data across cloud storage providers. In this paper we focus on the need to identify an algorithm for encoding and reassembling the data from the clouds. Erasure codes have been introduces more than three decades ago. Due to new technology trends and powerful hardware, new codes as well as improvements on classic codes have been developed recently. Therefore, we provide an overview of the current state of erasure codes. Further, we introduce the relevant codes in detail and compare them on the basis of identified criteria that are relevant to their application in a cloud context. Furthermore, we take a look at the current open source libraries, that support the discussed algorithms. The comparative study will help us to identity the best algorithm for our Cloud-RAID system.