Sparsity Exploiting Erasure Coding for Resilient Storage and Efficient   I/O Access in Delta based Versioning Systems
  In this paper we study the problem of storing reliably an archive of versioned data. Specifically, we focus on systems where the differences (deltas) between subsequent versions rather than the whole objects are stored - a typical model for storing versioned data. For reliability, we propose erasure encoding techniques that exploit the sparsity of information in the deltas while storing them reliably in a distributed back-end storage system, resulting in improved I/O read performance to retrieve the whole versioned archive. Along with the basic techniques, we propose a few optimization heuristics, and evaluate the techniques' efficacy analytically and with numerical simulations. 
J. Harshan, Fr\'ed\'erique Oggier and Anwitaman Datta
cs.IT cs.DC math.IT