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From "Ibrahim El-sanosi (PGR)" <i.s.el-san...@newcastle.ac.uk>
Subject 3-server Zab cluster
Date Mon, 28 Sep 2015 11:19:06 GMT
In Zab, assume we have a cluster consists of 3-servers. To deliver a write request, it must
run 3 communication steps proposal, acknowledgement and commit.
As Zab uses reliable FIFO, it is possible to remove commit round. As soon as a follower receives
a proposal, it logs, sends an ACK and commits locally. Upon receiving ACK from any follower,
leader commits a proposal locally, no COMMIT message need to be sent to followers. In this
case, all servers commit a proposal in two round-trips, resulting in reducing latency particularly
in followers.

Note that this optimization can only work in 3-servers cluster (follower reaches a majority
as soon as it acks).
Does anyone see any problems with such (small) optimization?
Ibrahim

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