TierStore: A Distributed Storage System for Developing Regions Michael Demmer, Bowei Du, and Sonesh Surana {demmer,bowei,sonesh}@cs.berkeley.edu Abstract The distribution of electronic information is an indis- pensable tool of businesses and individuals in coun- tries throughout world. However, the benefits of the information age have largely failed to permeate devel- oping regions. Traditional approaches to information distribution are rendered inadequate by poor quality power and networking. While many individual initia- tives seek to redress this situation, they for the most part lack any infrastructure upon which to build their applications, and rely instead on piecemeal and ad- hoc solutions. This paper presents TierStore, a distributed storage system specifically targeted for deployment in devel- oping regions. The TierStore system offers a plat- form for information dissemination that specifically addresses the problems caused by poor underlying in- frastructure. As such, TierStore presents a robust de- velopment framework and platform that can be lever- aged for applications in the developing world. 1 Introduction Networked communication, after years of evolution, has become an indispensable tool for the purposes of commercial transactions, financial services, social in- teraction, information dissemination, and many other services in many countries of the world. However, the gap between developed and developing regions re- garding access to such communication has also grown over the same years. Most rural regions suffer from financial, geographi- cal, infrastructure, and power constraints that have largely prohibited the development of a reliable com- munications network. Today there are about 4 bil- lion people that live in the absence of any access to communication services[9]. Given the impact that communication networks have had on developed re- gions, their potential impact on the developing re- gions, which comprise most of the world’s population, is even more compelling. We believe that an effective Information and Communications Technology (ICT) infrastructure is a necessary substrate for economic development as it enables more effective local govern- ment and deeper penetration of educational, health, and market information. However, many of the design principles for ICT in- frastructure in the developed world assume abun- dant power, reliable networking, and relatively so- phisticated users. Yet any infrastructure for de- veloping regions must be able to cope with unre- liable power, intermittent networking, illiterate end users, and orders of magnitude less economic power. The Technology and Infrastructure for Developing Regions (TIER) initiative is one proposal that ad- dresses these problems through the multidisciplinary approach of co-designing low cost, low power, flexible, intuitive devices with networks that are character- ized by low bandwidth, high delay, and intermittent connectivity[1]. Internet Data Center Proxy Satellite Devices Tier 1 Tier 2 Bus Tier 3 Figure 1: 3 Tier Architecture As shown in Figure 1, the architecture espoused by TIER has three layers. The first layer consists of a large data center. Much like the developed world, the data center has reliable power, high storage and powerful computation capabilities. It is also well con- nected to the backbone, and is typically located in an urban area. Through amortization of resources, a single data center can support millions of users using 1