9,402 research outputs found
Two-layer Locally Repairable Codes for Distributed Storage Systems
In this paper, we propose locally repairable codes (LRCs) with optimal
minimum distance for distributed storage systems (DSS). A two-layer encoding
structure is employed to ensure data reconstruction and the designated repair
locality. The data is first encoded in the first layer by any existing maximum
distance separable (MDS) codes, and then the encoded symbols are divided into
non-overlapping groups and encoded by an MDS array code in the second layer.
The encoding in the second layer provides enough redundancy for local repair,
while the overall code performs recovery of the data based on redundancy from
both layers. Our codes can be constructed over a finite field with size growing
linearly with the total number of nodes in the DSS, and facilitate efficient
degraded reads.Comment: This paper has been withdrawn by the author due to inaccuracy of
Claim
Content-access QoS in peer-to-peer networks using a fast MDS erasure code
This paper describes an enhancement of content access Quality of Service in peer to peer (P2P) networks. The main idea is to use an erasure code to distribute the information over the peers. This distribution increases the usersâ choice on disseminated encoded data and therefore statistically enhances the overall throughput of the transfer. A performance evaluation based on an original model using the results of a measurement campaign of sequential and parallel downloads in a real P2P network over Internet is presented. Based on a bandwidth distribution, statistical content-access QoS are guaranteed in function of both the content replication level in the network and the file dissemination strategies. A simple application in the context of media streaming is proposed. Finally, the constraints on the erasure code related to the proposed system are analysed and a new fast MDS erasure code is proposed, implemented and evaluated
Explicit MDS Codes for Optimal Repair Bandwidth
MDS codes are erasure-correcting codes that can correct the maximum number of
erasures for a given number of redundancy or parity symbols. If an MDS code has
parities and no more than erasures occur, then by transmitting all the
remaining data in the code, the original information can be recovered. However,
it was shown that in order to recover a single symbol erasure, only a fraction
of of the information needs to be transmitted. This fraction is called
the repair bandwidth (fraction). Explicit code constructions were given in
previous works. If we view each symbol in the code as a vector or a column over
some field, then the code forms a 2D array and such codes are especially widely
used in storage systems. In this paper, we address the following question:
given the length of the column , number of parities , can we construct
high-rate MDS array codes with optimal repair bandwidth of , whose code
length is as long as possible? In this paper, we give code constructions such
that the code length is .Comment: 17 page
FNT-based reed-solomon erasure codes
This paper presents a new construction of Maximum-Distance Separable (MDS) Reed-Solomon erasure codes based on Fermat Number Transform (FNT). Thanks to FNT, these codes support practical coding and decoding algorithms with complexity O(n log n), where n is the number of symbols of a codeword. An open-source implementation shows that the encoding speed can reach 150Mbps for codes of length up to several 10,000s of symbols. These codes can be used as the basic component of the Information Dispersal Algorithm (IDA) system used in a several P2P systems
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