I am pleased to announce that I'll be speaking at this year's QCon London. I'll be speaking in the "Modern CS in the real world" track, hosted by none other than Adrian Colyer, from the morning paper. The abstract for my talk, Making the Impossible Possible is as follows: In this talk, we explore how to construct resilient [...]
Just like humans organising to meet for coffee, computers need ways of organising themselves. Heidi Howard, of the System Research Group at University of Cambridge explains the basics.
Last Monday we looked at Tango, a system for replicating a data structure to provide linearizable semantics and fault-tolerance. Tango is built up on CORFU, a replicated log, built over storage nodes. This paper notes article covers "CORFU: A distributed shared log" also by Balakrishnan et al. from TOCS December 2013. I believe that this [...]
The following is a paper notes article on "Tango: Distributed Data Structures over a Shared Log" by Balakrishnan et al. from SOSP 2013. The article focus on the main body of the paper and I will cover Tango's streaming and transaction support in a separate article, sometime in the future. I have covered this paper [...]
I asked a question on today's BBC radio 4 show "Any questions?", http://www.bbc.co.uk/programmes/b06b3ny4, skip to 42:07 to hear me nervously ask "How can we protect the rights of citizens in an increasingly digital world?" and hear the panel's response. The responses where fairly disappointing but it helps to keep the debate alive.
So far in this study, we have only considered the aggregated measurements and how they vary depending on the VMs used. In this post, we will considered how the RTT measurements may have changed over time. The following 5 plots show the RTT as observed by each machine over time. The y axis stops as [...]
In this post we will be looking at the results for the Azure latency Pilot study described last week. Yesterday, we started by looking at the aggregated results and found that the measured RTT was larger then expected. Today, we will look at how the results vary depending on which VMs the measurements where taken [...]
This is post we will be looking at the results for the Azure latency Pilot study described last week. We will starting by looking at the aggregate results, disregarding the time a measurement was taken and which machines the measurement was taken between. The 22332 data points have been processed in Python3, in particular using [...]
This post, the first in a short series, discusses a simple overnight pilot study of measuring network characteristics on Microsoft Azure. This study was to be the first of many. Its purpose was to test the tools and gave some initial measurements, thus informing the the design of more substantial measurement studies in the future. [...]
TL;DR: Run distributed systems using majority quorum on an odd number of machines. Paxos, Raft, Viewstamped Replication and many other consensus algorithms operate on majority quorums. A majority quorum is any subset of nodes containing at least a strict majority of nodes. These algorithms all require a majority quorum to agree to a value before its [...]