Helal Assi, M.Sc. Thesis Seminar
Wednesday, 14.6.2017, 15:00
Distributed and cloud storage systems today are required to tolerate the failure or unavailability of some
of the nodes in the system. The simplest and most commonly used way to accomplish this task is replication,
whereby every node is replicated several times, usually three. This solution has clear advantages due to its
simplicity, fast recovery, and efficient availability. However, it entails a large storage overhead which
becomes costly in large storage systems.
In this work we study two families of codes with availability for distributed storage, namely private information
retrieval (PIR) codes and batch codes. A code is said to have availability t if every code symbol can be
recovered from t mutually disjoint recovering sets of other symbols. We provide several constructions of PIR
and batch codes for various values of the availabilty parameter, which some of them are optimal.