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You searched for subject:(Locally repairable codes). Showing records 1 – 2 of 2 total matches.

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University of Minnesota

1. Agarwal, Abhishek. Data Estimation and Recovery for Distributed Systems.

Degree: PhD, Electrical/Computer Engineering, 2018, University of Minnesota

This thesis is devoted to a range of data estimation problems in applied mathematics and signal processing motivated by applications in data storage, broadcast transmission, and group testing. We use a common toolset of diverse information theoretic, combinatorial and probabilistic arguments to attack these problems. There are two primary themes in the data estimation problems we look at : 1. Estimation of data when part of the data is lost 2. Data estimation when constraints on input sparsity are known The first estimation problem is well known in classical coding theory. We look at a more recently emerging variant of the classical problem in the context of handling constraints related to data storage and transmission. Large data storage networks encounter frequent server failures which need to be repaired in a cost effective manner. A simple technique of data replication, although inefficient in terms of storage, provides suprisingly low repair costs. Error-correcting codes, on the other hand, are efficient in terms of storage but require large repair cost for single server failures. The trade-off between storage and repair cost has been studied intensively in the past few years due to its significance to big data storage. We study a particular class of codes, called Locally Repairable Codes, that optimize this trade-off for a specific cost metric, locality, that denotes the number of other servers accessed to repair a single failure. For traditional error-correcting codes trade-offs (bounds) between their parameters (minimum distance, code size, and length) have been well studied. Even for Locally Repairable Codes, analogous bounds have been discovered especially for constructions of the codes in a large field. We derive bounds on the size of Locally Repairable Codes for small alphabets. Another issue that is crucial for the design of distributed systems is their resilience to adversarial attacks. We want to guarantee security of the data from an eavesdropper that can access any subset of a fixed number of storage nodes. We analyze the limits and constructions of secure codes for distributed storage systems. Our techniques are readily applicable to a variety of distributed systems such as systems with co-operative local repair (i.e. more than one failures occur simultaneously) and distributed systems represented by arbitrary graphs with vertices corresponding to storage servers. We also study an interesting practical problem related to repairable codes on graphs known as Index Coding. Consider a broadcast transmitter that wants to send a separate stream of data to all the users in a network such that users may have information about data corresponding to some of the other users. We can represent this side information with a graph on the set of users as vertices, where the neighbors of the vertices represents their side information. Our aim is to minimize the broadcast transmissions while satisfying the requirements of each user. For the same graph representing the storage nodes and the users in the distributed…

Subjects/Keywords: group testing; locally repairable codes; secure codes

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Agarwal, A. (2018). Data Estimation and Recovery for Distributed Systems. (Doctoral Dissertation). University of Minnesota. Retrieved from http://hdl.handle.net/11299/201091

Chicago Manual of Style (16th Edition):

Agarwal, Abhishek. “Data Estimation and Recovery for Distributed Systems.” 2018. Doctoral Dissertation, University of Minnesota. Accessed June 20, 2019. http://hdl.handle.net/11299/201091.

MLA Handbook (7th Edition):

Agarwal, Abhishek. “Data Estimation and Recovery for Distributed Systems.” 2018. Web. 20 Jun 2019.

Vancouver:

Agarwal A. Data Estimation and Recovery for Distributed Systems. [Internet] [Doctoral dissertation]. University of Minnesota; 2018. [cited 2019 Jun 20]. Available from: http://hdl.handle.net/11299/201091.

Council of Science Editors:

Agarwal A. Data Estimation and Recovery for Distributed Systems. [Doctoral Dissertation]. University of Minnesota; 2018. Available from: http://hdl.handle.net/11299/201091


University of Texas – Austin

2. -9790-6500. New coding techniques for distributed storage systems: enabling locality, availability and security.

Degree: Electrical and Computer Engineering, 2015, University of Texas – Austin

Distributed storage systems (a.k.a. cloud storage networks) are becoming increasingly important, given the need to put away vast amounts of data that are being generated, analyzed and accessed across multiple disciplines today. Besides serving as backbone systems for large institutions such as CERN, Google and Microsoft, distributed storage systems have been instrumental in the emergence and rapid growth of the modern cloud computing framework. This dissertation takes a coding theoretic approach to address key issues related to designing these systems. First, the problem of enabling efficient mechanisms for restoring the state of the system after storage node failures in considered. In particular, this dissertation studies locally repairable codes that allow for reconstruction of the content stored on a failed node by contacting a small number of intact nodes. Since resilience to permanent loss of the stored information in the event of catastrophic failures is of primary interest in storage systems, explicit constructions for locally repairable codes with optimal minimum distance are presented. This dissertation also designs locally repairable codes that minimize repair-bandwidth, i.e., the amount of data downloaded during a node repair, in addition to the number of intact nodes contributing to the repair process. This dissertation further investigates a generalization of locally repairable codes where codes with the following property are studied: any small set of failed nodes is recoverable from a small number of other intact nodes. This is referred to as cooperative local repair. The main contributions in this regard are bounds on the minimum distance and the dimension of such codes, as well as explicit constructions of families of codes that enable cooperative local repair. The second issue addressed in this dissertation concerns management of hot data, i.e., the frequently accessed information. Towards this, the codes that allow for parallel accesses to information blocks are considered. This part of the dissertation explores the rate vs. minimum distance trade-off for such codes and presents explicit constructions of the codes that have high rate and large minimum distance while supporting (potentially scaling number of) parallel accesses to the stored information. One of the main contributions of the dissertation in this direction is a novel graph theoretic approach to construct batch codes. The batch codes as defined in the literature enable load balancing in a storage system in the sense that multiple requests for information blocks can be served in a parallel manner without downloading too much data from any particular storage node. Finally, this dissertation considers the issue of designing secure coding scheme for distributed storage systems. Given the decentralized nature of these systems and their increasing utilization to store valuable and confidential information, it is desirable that they be resilient against eavesdropping attacks. The problem of characterizing perfect secrecy capacity of… Advisors/Committee Members: Vishwanath, Sriram (advisor), Baccelli, Francois (committee member), Dimakis, Alexandros G (committee member), Mazumdar, Arya (committee member), Zuckerman, David (committee member).

Subjects/Keywords: Coding for distributed storage; Locally repairable codes; Regenerating codes; Code repair; Cooperative repair; Secure distributed storage

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

-9790-6500. (2015). New coding techniques for distributed storage systems: enabling locality, availability and security. (Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/32413

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

-9790-6500. “New coding techniques for distributed storage systems: enabling locality, availability and security.” 2015. Thesis, University of Texas – Austin. Accessed June 20, 2019. http://hdl.handle.net/2152/32413.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

-9790-6500. “New coding techniques for distributed storage systems: enabling locality, availability and security.” 2015. Web. 20 Jun 2019.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Vancouver:

-9790-6500. New coding techniques for distributed storage systems: enabling locality, availability and security. [Internet] [Thesis]. University of Texas – Austin; 2015. [cited 2019 Jun 20]. Available from: http://hdl.handle.net/2152/32413.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

-9790-6500. New coding techniques for distributed storage systems: enabling locality, availability and security. [Thesis]. University of Texas – Austin; 2015. Available from: http://hdl.handle.net/2152/32413

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Not specified: Masters Thesis or Doctoral Dissertation

.