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https://issues.apache.org/jira/browse/HDFS-3092?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13271098#comment-13271098
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Eli Collins commented on HDFS-3092:
-----------------------------------
Notes from the meeting:
* Discussed the two approaches for the client side (HDFS-3077 and HDFS-3092),
the server sides are similar modulo small differences in recovery. Discussed
the tradeoffs in terms of going down to n-1 servers/requiring a quorum vs
latency sensitivity, in the context of typical cluster configurations. Think
it's possible to wed the client side of 3077 (quorum journal) to the server
side of 3092 (journal daemon). Will pursue further on jira.
* Discussed journal-based fencing. Current NN fencers are not needed when the
journal handles fencing.
* Discussed IP based failover and stonith, primary motivation for the current
approach is that other master services that are not yet HA often run on the
same machines, stonith doesn't work here.
* Discussed making the state machine for auto failover more explicit
* Discussed separate vs embedded FCs, separate works well for now, though
currently means we'll need a FC per service that gets failover (vs embedding a
FC in each service that will need failover)
> Enable journal protocol based editlog streaming for standby namenode
> --------------------------------------------------------------------
>
> Key: HDFS-3092
> URL: https://issues.apache.org/jira/browse/HDFS-3092
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: ha, name-node
> Affects Versions: 0.24.0, 0.23.3
> Reporter: Suresh Srinivas
> Assignee: Suresh Srinivas
> Attachments: ComparisonofApproachesforHAJournals.pdf, JNStates.png,
> MultipleSharedJournals.pdf, MultipleSharedJournals.pdf,
> MultipleSharedJournals.pdf, Removingfilerdependency.pdf
>
>
> Currently standby namenode relies on reading shared editlogs to stay current
> with the active namenode, for namespace changes. BackupNode used streaming
> edits from active namenode for doing the same. This jira is to explore using
> journal protocol based editlog streams for the standby namenode. A daemon in
> standby will get the editlogs from the active and write it to local edits. To
> begin with, the existing standby mechanism of reading from a file, will
> continue to be used, instead of from shared edits, from the local edits.
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