Zhiying Wang, Caltech May 25, 2:00pm. EEB 248
Abstract: Erasure-correcting codes are the basis of the ubiquitous RAID schemes for storage systems, where disks correspond to symbols in the code. Specifically, RAID schemes are based on MDS (maximum distance separable) array codes that enable optimal storage and efficient encoding and decoding algorithms. With r redundancy symbols, an MDS code is able to reconstruct the original information if no more than r symbols are erased. For example, consider an MDS code that can correct two erasures. It is clear that when two symbols are erased, one needs to access or read all the remaining information to rebuild the erasures. However, an interesting and practical question is: What is the smallest amount of information that one needs to access in order to correct a single erasure? Previous work showed that the fraction of accessed information is bounded between 1/2 and 3/4, however, the exact value was left as an open problem. In this talk we will show that 1/2 is achievable and give an explicit construction of a family of MDS array codes with optimal rebuilding for any number of erasures less than r.
Zhiying Wang received her Bachelor's Degree in Department of Electronic Engineering at Tsinghua University, Beijing, China in 2007 and the M.S. degree in Electrical Engineering from California Institute of Technology, Pasadena, USA in 2009. She is currently a Ph.D candidate in Electrical Engineering in California Institute of Technology. Her research interest includes error-correcting codes, constrained coding, and coding techniques for storage devices such as flash memory, phase-change memory, and disks.
Host: Alex Dimakis, dimakis [at] usc.edu
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