Trapezoid Quorum Protocol Dedicated to Erasure Resilient Coding Based Schemes

In distributed storage systems like parallel file systems or storage virtualization middleware, data replication is the mainly used solution to implement data avaialability. The more replicas are distributed among nodes, the more robust is the storage system. However, the price to pay for this dependability becomes significant, due to both direct costs (the price of disks) and indirect costs (the energy consumption of this large amount of disks needed). In order to lower the disk space needed for a given availalbility, Erasure Resilient Codes (referred to as ERC after this) are of interest and start to be implemented in this context. However, the use of such codes involves some new problems in data management. In fact, if some constraints like data concurrency can be solved using classical ways, others like coherency protocols need some adaptations in order to fit this context. In this paper, we present an adaptation of trapezoid protocol in the context of ERC schemes (instead of full replication). This new quorum protocol shows an increase of storage space efficiency while maintaining a high level of availability for read and writes operations.