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Codes for Data Storage

16 Nov
Wednesday, 11/16/2016 4:00pm to 5:00pm
Computer Science Building, Room 150/151
Distinguished Lecturer Series

Recent developments in data storage are sparking development of new research directions in Coding and Information Theory, and the speed with which new insights have been translated into commercial systems is quite remarkable.

Data storage experts were accustomed to using MDS codes to store k symbols across N disks in a RAID disk array, so as to be able to recover from N-k disk failures. The drawback is that access to at least k disks is required to correct a single disk failure. As data centers have grown, the need to reduce communication has become more acute. Coding theorists were accustomed to focus entirely on distance between codewords, but the need to reduce communications bandwidth is causing coding theorists to explore codes with small parity checks. I will describe some recent developments.

At the physical level, hard disk drives are losing ground to Flash because they do not support random access, their moving parts consume significant power and they have relatively slow read and write speeds.  The adoption of non-volatile memory in large data centers is making a particular shortcoming of Flash more visible; the fact that a memory cell can only support a limited number of writes before it fails, and that this number is expected to decrease significantly as the minimum feature size of Flash transistors shrinks. I will describe how to extend the lifetime of Flash memory by increasing the number of writes that are possible before erasure is necessary.  

Biography: Robert Calderbank is Director of the Information Initiative at Duke University, where he is Professor of Mathematics and Electrical Engineering. Prior to joining Duke as Dean of Natural Sciences in 2010, he directed the Program in Applied and Computational Mathematics at Princeton University. Prior to joining Princeton in 2004 he was Vice President for Research at AT&T, in charge of what may have been the first industrial research lab where the primary focus was Big Data.

Professor Calderbank is well known for contributions to voiceband modem technology, to quantum information theory, and for co-invention of space-time codes for wireless communication. His research papers have been extensively cited and his inventions are found in billions of consumer devices. Professor Calderbank was elected to the National Academy of Engineering in 2005 and has received a number of awards, including the 2013 IEEE Hamming Medal for his contributions to information transmission, and the 2015 Claude E. Shannon Award.


A reception will be held at 3:40 p.m. in the atrium, outside the presentation room.

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