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https://issues.apache.org/jira/browse/HDFS-4945?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13696278#comment-13696278
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Yonghwan Kim commented on HDFS-4945:
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Dear Suresh Srinivas,
Thank you for your helpful comments.
1. As you said, in the case of HDFS 2.0, an NFS is necessary to share edit logs
between 2 NNs.
However, we simple thought an NFS can be a new SPOF, so some way to guarantee
the fault-tolerance of an NFS should be needed (i.e. RAID or network
multiplexing). We just express it(fault-tolerant technique) in a word 'reliable
sophisticated storage'.
Actually, latest version of HDFS 2.0(maybe 2.0.5) adopts QJM(HDFS-3077), and
one of its requirements is "No requirement for special hardware". Likewise, we
want to propose a new architecture using only commodity hardwares.
2&3. I deeply apologize for absence of detail information. I'm writing a
technical document (paper) (including background, related works, design, proof
of consistency) but not completed yet. Please wait for a while and I'll add
some information here before complete the writing our paper.
4. We just had tested the system's overhead for synchronizing among NNs with
some dummy data. After the completion of writing document, we will implement a
prototype with utmost effort.
(We already had proved that our system is consistent in theory)
Affects Version is my mistake. I'll edit it to HDFS-1623. Thanks.
Sorry for my poor English.
> A Distributed and Cooperative NameNode Cluster for a Highly-Available HDFS
> --------------------------------------------------------------------------
>
> Key: HDFS-4945
> URL: https://issues.apache.org/jira/browse/HDFS-4945
> Project: Hadoop HDFS
> Issue Type: New Feature
> Components: auto-failover
> Affects Versions: HA branch (HDFS-1623)
> Reporter: Yonghwan Kim
> Labels: documentation
>
> See the following comment for detailed description.
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