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Add PDF of draft 0.9 of high-level-chain-mgr.pdf

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Scott Lystig Fritchie 2015-05-05 19:22:29 +09:00
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@ -8,10 +8,10 @@ Erlang documentation, please use this link:
### chain-self-management-sketch.org ### chain-self-management-sketch.org
__chain-self-management-sketch.org__ is an introduction to the __chain-self-management-sketch.org__ is a mostly-deprecated draft of
self-management algorithm proposed for Machi. This algorithm is an introduction to the
(hoped to be) sufficient for managing the Chain Replication state of a self-management algorithm proposed for Machi. Most material has been
Machi cluster. moved to the __high-level-chain-mgr.pdf__ document.
### high-level-machi.pdf ### high-level-machi.pdf
@ -30,3 +30,35 @@ Machi. Its abstract:
> consistency features --- strong consistency design will be discussed > consistency features --- strong consistency design will be discussed
> in a separate document. > in a separate document.
### high-level-chain-mgr.pdf
__high-level-chain-mgr.pdf__ is an overview of the techniques used by
Machi to manage Chain Replication metadata state. It also provides an
introduction to the Humming Consensus algorithm. Its abstract:
> Machi is an immutable file store, now in active development by Basho
> Japan KK. Machi uses Chain Replication to maintain strong consistency
> of file updates to all replica servers in a Machi cluster. Chain
> Replication is a variation of primary/backup replication where the
> order of updates between the primary server and each of the backup
> servers is strictly ordered into a single ``chain''. Management of
> Chain Replication's metadata, e.g., ``What is the current order of
> servers in the chain?'', remains an open research problem. The
> current state of the art for Chain Replication metadata management
> relies on an external oracle (e.g., ZooKeeper) or the Elastic
> Replication algorithm.
>
> This document describes the Machi chain manager, the component
> responsible for managing Chain Replication metadata state. The chain
> manager uses a new technique, based on a variation of CORFU, called
> ``humming consensus''.
> Humming consensus does not require active participation by all or even
> a majority of participants to make decisions. Machi's chain manager
> bases its logic on humming consensus to make decisions about how to
> react to changes in its environment, e.g. server crashes, network
> partitions, and changes by Machi cluster admnistrators. Once a
> decision is made during a virtual time epoch, humming consensus will
> eventually discover if other participants have made a different
> decision during that epoch. When a differing decision is discovered,
> new time epochs are proposed in which a new consensus is reached and
> disseminated to all available participants.

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