Babel Storage: Uncoordinated Content Delivery from Multiple Coded Storage Systems

TL;DR

This paper explores how using diverse coding schemes across multiple storage systems can significantly reduce content delivery inefficiencies in future content-centric networks, emphasizing minimal coordination.

Contribution

It characterizes the storage-transmission tradeoff with uniform coding and demonstrates that code diversity improves efficiency in uncoordinated content delivery.

Findings

Diverse coding schemes reduce delivery overhead.

Uniform coding leads to significant inefficiencies.

Mixing Reed-Solomon, LDPC, and network codes achieves near-optimal performance.

Abstract

In future content-centric networks, content is identified independently of its location. From an end-user's perspective, individual storage systems dissolve into a seemingly omnipresent structureless `storage fog'. Content should be delivered oblivious of the network topology, using multiple storage systems simultaneously, and at minimal coordination overhead. Prior works have addressed the advantages of error correction coding for distributed storage and content delivery separately. This work takes a comprehensive approach to highlighting the tradeoff between storage overhead and transmission overhead in uncoordinated content delivery from multiple coded storage systems. Our contribution is twofold. First, we characterize the tradeoff between storage and transmission overhead when all participating storage systems employ the same code. Second, we show that the resulting stark inefficiencies can be avoided when storage systems use diverse codes. What is more, such code diversity is not just technically desirable, but presumably will be the reality in the increasingly heterogeneous networks of the future. To this end, we show that a mix of Reed-Solomon, low-density parity-check and random linear network codes achieves close-to-optimal performance at minimal coordination and operational overhead.