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https://issues.apache.org/jira/browse/HADOOP-10641?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14055505#comment-14055505
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Aaron T. Myers commented on HADOOP-10641:
-----------------------------------------
HDFS-6469 still has several unanswered or un-retracted objections, perhaps most
notably this one from Suresh:
{quote}
I am very uncomfortable about adding all this complexity into HDFS.
{quote}
and this one from Todd:
{quote}
Lastly, a fully usable solution would be available to the community at large,
whereas the design you're proposing seems like it will only be usably
implemented by a proprietary extension (I don't consider the ZK "reference
implementation" likely to actually work in a usable fashion).
{quote}
I personally share both of these concerns with Suresh and Todd, specifically
that this design seems overly-complex and does not add much (or perhaps any)
benefit over a simpler solution that builds on the current HA system in Hadoop,
and I'm concerned about baking in dependence on a proprietary 3rd party system
for HA capabilities.
My main point here is that this work (HADOOP-10641) will not be useful to
Hadoop except in the context of HDFS-6469. So, I'm not OK with committing this
to trunk, at least until there's general agreement that HDFS-6469 is a
reasonable design that we should move forward with in Hadoop. As it stands, I
don't think there is such agreement; I certainly have not been convinced of
this yet. I'm OK with you committing this to a development branch if you want
to try to make progress that way, though.
> Introduce Coordination Engine
> -----------------------------
>
> Key: HADOOP-10641
> URL: https://issues.apache.org/jira/browse/HADOOP-10641
> Project: Hadoop Common
> Issue Type: New Feature
> Affects Versions: 3.0.0
> Reporter: Konstantin Shvachko
> Assignee: Plamen Jeliazkov
> Attachments: HADOOP-10641.patch, HADOOP-10641.patch,
> HADOOP-10641.patch, hadoop-coordination.patch
>
>
> Coordination Engine (CE) is a system, which allows to agree on a sequence of
> events in a distributed system. In order to be reliable CE should be
> distributed by itself.
> Coordination Engine can be based on different algorithms (paxos, raft, 2PC,
> zab) and have different implementations, depending on use cases, reliability,
> availability, and performance requirements.
> CE should have a common API, so that it could serve as a pluggable component
> in different projects. The immediate beneficiaries are HDFS (HDFS-6469) and
> HBase (HBASE-10909).
> First implementation is proposed to be based on ZooKeeper.
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