A disaster-resilient multi-content optical datacenter network architecture

Cloud services based on datacenter networks are becoming very important. Optical networks are well suited to meet the demands set by the high volume of traffic between datacenters, given their high bandwidth and low-latency characteristics. In such networks, path protection against network failures is generally ensured by providing a backup path to the same destination, which is link-disjoint to the primary path. This protection fails to protect against disasters covering an area which disrupts both primary and backup resources. Also, content/service protection is a fundamental problem in datacenter networks, as the failure of a single datacenter should not cause the disappearance of a specific content/service from the network. Content placement, routing and protection of paths and content are closely related to one another, so the interaction among these should be studied together. In this work, we propose an integrated ILP formulation to design an optical datacenter network, which solves all the above-mentioned problems simultaneously. We show that our disaster protection scheme exploiting anycasting provides more protection, but uses less capacity, than dedicated single-link protection. We also show that a reasonable number of datacenters and selective content replicas with intelligent network design can provide survivability to disasters while supporting user demands

Probabilistic Shared Risk Link Groups Modeling Correlated Resource Failures Caused by Disasters

To evaluate the expected availability of a backbone network service, the administrator should consider all possible failure scenarios under the specific service availability model stipulated in the corresponding service-level agreement. Given the increase in natural disasters and malicious attacks with geographically extensive impact, considering only independent single component failures is often insufficient. This paper builds a stochastic model of geographically correlated link failures caused by disasters to estimate the hazards an optical backbone network may be prone to and to understand the complex correlation between possible link failures. We first consider link failures only and later extend our model also to capture node failures. With such a model, one can quickly extract essential information such as the probability of an arbitrary set of network resources to fail simultaneously, the probability of two nodes to be disconnected, the probability of a path to survive a disaster. Furthermore, we introduce standard data structures and a unified terminology on Probabilistic Shared Risk Link Groups (PSRLGs), along with a pre-computation process, which represents the failure probability of a set of resources succinctly. In particular, we generate a quasilinear-sized data structure in polynomial time, which allows the efficient computation of the cumulative failure probability of any set of network elements. Our evaluation is based on carefully pre-processed seismic hazard data matched to real-world optical backbone network topologies.Accepted author manuscriptEmbedded and Networked System

Why Information Matters: A Foundation for Resilience

Embracing Change: The Critical Role of Information, a research project by the Internews' Center for Innovation & Learning, supported by the Rockefeller Foundation, combines Internews' longstanding effort to highlight the important role ofinformation with Rockefeller's groundbreaking work on resilience. The project focuses on three major aspects:- Building knowledge around the role of information in empowering communities to understand and adapt to different types of change: slow onset, long-term, and rapid onset / disruptive;- Identifying strategies and techniques for strengthening information ecosystems to support behavioral adaptation to disruptive change; and- Disseminating knowledge and principles to individuals, communities, the private sector, policymakers, and other partners so that they can incorporate healthy information ecosystems as a core element of their social resilience strategies

Identifying common problems in the acquisition and deployment of large-scale software projects in the US and UK healthcare systems

Public and private organizations are investing increasing amounts into the development of healthcare information technology. These applications are perceived to offer numerous benefits. Software systems can improve the exchange of information between healthcare facilities. They support standardised procedures that can help to increase consistency between different service providers. Electronic patient records ensure minimum standards across the trajectory of care when patients move between different specializations. Healthcare information systems also offer economic benefits through efficiency savings; for example by providing the data that helps to identify potential bottlenecks in the provision and administration of care. However, a number of high-profile failures reveal the problems that arise when staff must cope with the loss of these applications. In particular, teams have to retrieve paper based records that often lack the detail on electronic systems. Individuals who have only used electronic information systems face particular problems in learning how to apply paper-based fallbacks. The following pages compare two different failures of Healthcare Information Systems in the UK and North America. The intention is to ensure that future initiatives to extend the integration of electronic patient records will build on the ‘lessons learned’ from previous systems