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https://issues.apache.org/jira/browse/HDFS-4025?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13480181#comment-13480181
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Sanjay Radia commented on HDFS-4025:
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Todd, I am fine with making the full vs partial sync configurable if you
prefer. However I would like to continue the discussion we started in HDFS-3077.
The relevant comments are
[comment1|
https://issues.apache.org/jira/browse/HDFS-3077?focusedCommentId=13473384&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13473384]
[comment2
|https://issues.apache.org/jira/browse/HDFS-3077?focusedCommentId=13473783&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13473783]
> QJM: Sychronize past log segments to JNs that missed them
> ---------------------------------------------------------
>
> Key: HDFS-4025
> URL: https://issues.apache.org/jira/browse/HDFS-4025
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: ha
> Affects Versions: QuorumJournalManager (HDFS-3077)
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Fix For: QuorumJournalManager (HDFS-3077)
>
>
> Currently, if a JournalManager crashes and misses some segment of logs, and
> then comes back, it will be re-added as a valid part of the quorum on the
> next log roll. However, it will not have a complete history of log segments
> (i.e any individual JN may have gaps in its transaction history). This
> mirrors the behavior of the NameNode when there are multiple local
> directories specified.
> However, it would be better if a background thread noticed these gaps and
> "filled them in" by grabbing the segments from other JournalNodes. This
> increases the resilience of the system when JournalNodes get reformatted or
> otherwise lose their local disk.
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