Distributed storage systems provide fast and reliable access to data by intro- ducing redundancy for stored les. The most common approach of adding re- dundant information is by repetition and erasure codes. Two main processes in a distributed storage system are reconstruction of original le and regenerat- ing a new node. These two processes require bandwidth, which are termed as reconstruction-bandwidth and repair-bandwidth. The current literature treat- s these two processes separately. That is, there are methods to reduce the reconstructing bandwidth without considering the repair-bandwidth, and also there are methods to reduce the repair-bandwidth. We study these two pro- cesses together and try to jointly minimize the reconstruction-bandwidth and repair-bandwidth. We observe a method that has the minimum reconstruction- bandwidth might have large amount of repair-bandwidth and vice versa. We propose codes which minimizes the sum of the repair-bandwidth and reconstruction- bandwidth. The main contribution of this thesis is nding an value of repair locality r (number of nodes connected during node repair) and devising two coding meth- ods in which total bandwidth approximates to be half reduced compared with MSR and MBR when k ! 1 under the condition that 1 6 r 6 k.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:kth-160952 |
| Date | January 2014 |
| Creators | Yan, Fan |
| Publisher | KTH, Kommunikationsteori |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | EES Examensarbete / Master Thesis ; XR-EE-KT 2014:008 |
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