62 lines
3.2 KiB
TeX
62 lines
3.2 KiB
TeX
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\begin{itemize}
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\item
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Recursive quorum systems are all non-dominated bicoteries. We can view the
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tree as a way to generate an arbitrary set of read quorums. Then we just
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bubble down dual to compute write quorums.
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\item
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The theory of coteries and decomposition has been very well studied. The
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one thing that seems a little less studied is the relationship between load
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and bicoteries. Can we find a nice way to find an optimal load bicoterie?
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This is probably hard, but maybe something about bicoteries makes this
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easier than for coteries.
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\item
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If we wanted to develop a library for bicoteries, we would like to (a)
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allow people to form arbitrary bicoteries, (b) compute an optimal strategy
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for a bicotier, (c) efficiently pick quorums based on the strategy, and (d)
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efficiently determine if something is a superset of a quorum. We can do (a)
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with a library of dual-able operators like or and and along with some
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builtins for things like grids. (b) we can use LP with specializations. We
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might have to do something smart to get ``good' strategies (e.g.,
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balanced). For (d), we can just evaluate the tree or its dual or maybe use
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something more efficient like BDDs? For (c) I'm not completely sure. For
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some quorum systems, the number of quorums is exponential, so we wouldn't
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want to represent them explicitly. Ideally we could also find an optimal
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load bicoterie, but that's probably not going to happen. The library can
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also help compute fault tolerance and maybe load under failure and whatnot.
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How to compute fault tolerance with duplicates?
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\item
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Maybe we can run some practical experiments to show how important a good
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bicoterie is. Maybe we'll find it's not that important.
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\item
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Is there anything smart about reconfiguring or changing coteries on the
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fly? For example, grids are not good to go from 6 to 7 nodes. With
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bicoteries, we probably want to adjust on the fly as the read and write
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ratios change.
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\item
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Maybe we can introduce the idea that not all nodes have the same capacity.
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Some have higher load than others. We could bake that into the nodes like,
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a = Node("a", cap=1000).
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\item
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Maybe some nodes are also co-located, so the fault tolerance is a little
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different. How can we compute fault tolerance with duplicates anyway?
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\item
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Just for fun, we could probably cross compile to javascript and show how to
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subsume other quorum systems with our library. We should be able to subsume
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all if we use duplicates.
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\end{itemize}
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\TODO[michael]{Prove that for every read-write quorum system, there exists a coterie with at least as good load.}
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\TODO[michael]{The above shows that the optimal load quorum system is a non-dominated coterie. Maybe this is useful? We can generate every NDC?}
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\TODO[michael]{Understand how domination relates to subsumption.}
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\TODO[michael]{Understand dual-major, dual-minor, and self-dual.}
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\TODO[michael]{Extend these notions to read-write quorums.}
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\TODO[michael]{Enumerate all read-write quorums on four nodes and see the ones we can and can't subsume.}
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\TODO[michael]{Prove that if I have the read quorums R, then the write quorums are bar(R).}
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