Regarding ease-of-use, it’s often struck me when reviewing data systems papers that the evaluation sections are full of performance and correctness criteria, but only rarely is there any discussion of how well a system helps its target users achieve their
Distributed consensus and network reliability
All of the distributed consensus algorithms I have been reviewing recently (Paxos, Raft, Zab, Chang Maxemchuck, Viewstamped, … ) are based on a number of assumptions about the network environment, including the assumption that messages may be lost but are
The replicated state machine method of fault tolerance from 1980s
The first time I saw this method was when I went to work for Parallel Computer Systems, , later called Auragen, in the famous tech startup center of Englewood Cliffs, New Jersey. I commuted there from the East Village. (True story: I
circularity problems in distributed consensus
Distributed consensus involves organizing a collection of independent agents – processes or network sites – to agree on some value or sequence of values. Many distributed consensus methods depend on a leader-follower scheme in which the leader is an agent
Making Paxos face facts
Replaced by Paxos Demystified. Lamport’s “Paxos Made Simple” paper is notoriously hard to understand but at least part of the difficulty is that the algorithm changes radically in the middle of the presentation. The first part of the paper presents a
state equations in practice
When people think of mathematical models of state for programs and other computer systems, it’s natural and conventional to consider state as a map from symbolic names of state variable to values. This is an error for a number
State equations
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