Durable network coded distributed storage

In distributed cloud storages fault tolerance is maintained by regenerating the lost coded data from the surviving clouds. Recent studies suggest using maximum distance separable (MDS) network codes in cloud storage systems to allow efficient and reliable recovery after node faults. MDS codes are designed to use a substantial number of repair nodes and rely on centralized management and a static fully connected network between the nodes. However, in highly dynamic environments, like edge caching in communication networks or peer-to-peer networks, availability of the nodes and the communication links is very volatile. In these scenarios MDS codes functionality is limited. In this paper we study a non-MDS network coded approach, which operates in a decentralized manner and requires a small number of repair nodes for node recovery. We investigate long-term behavior and durability of the modeled system in terms of the storage life time, i.e. the number of the cycles of nodes failure and recovery after which the storage no longer have enough data to decode the original source packets. We demonstrate, analytically and numerically, the life time gains over uncoded storage.