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https://issues.apache.org/jira/browse/MESOS-1465?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14026006#comment-14026006
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Benjamin Mahler commented on MESOS-1465:
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Hey [~chengwei-yang], thanks for raising this issue! We definitely deliberated
on using {{\-\-num_masters}} to infer quorum size for safer operation, there
are a few things that were considered:
* {{\-\-num_masters}} allows us to infer the quorum size programatically.
* {{\-\-quorum}} places more control in the operators hands, e.g. one can set
{{quorum == num_masters}} if one so desires.
* {{\-\-quorum}} makes it clear that the flag is being used to determine log
quorum size, {{\-\-num_masters}} *might* be more likely to be glossed over and
not carefully understood by the operator. This is ultimately why we went with
{{\-\-quorum}}.
I would be happy to accept a patch that adds {{\-\-num_masters}} and makes it
required to have *exactly one of* (num_masters, quorum) specified. Can you post
your review here?
Looking way further ahead, we were also considering a {{\-\-masters}} flag that
takes the full list of masters in the ensemble (e.g.
{{--masters=localhost:5050,localhost:5051,localhost:5052}}). This would provide
additional safety by ensuring that the correct masters are present in the log
replica network, later we could use log re-configuration to safely change the
ensemble of masters. It allows us to infer quorum size.
> Use '--nr_of_masters' instead of '--quorum'
> -------------------------------------------
>
> Key: MESOS-1465
> URL: https://issues.apache.org/jira/browse/MESOS-1465
> Project: Mesos
> Issue Type: Improvement
> Components: master
> Affects Versions: 0.20.0
> Environment: master branch HEAD
> commit 5172630ae73b7c5f21e1d0e1840a3dc676816582
> Author: Benjamin Mahler <[email protected]>
> Date: Thu Jun 5 09:49:40 2014 -0700
> Added "implicit" reconciliation.
>
> Review: https://reviews.apache.org/r/22268
> Reporter: Chengwei Yang
> Assignee: Chengwei Yang
>
> --quorum option introduced for log replication when zookeeper used. Log
> replication is a great feature.
> However, '--quorum' is not very fit into, considering to below:
> # when using with zookeeper, user may confusing with quorum in zookeeper
> # user need to learn how quorum works, why it's necessary.
> While use '--nr_of_masters', the user is definitely know how many mesos
> masters in his/her clusters. It's quite simple and straight-forward.
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