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https://issues.apache.org/jira/browse/HBASE-4377?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13122367#comment-13122367
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Jonathan Hsieh commented on HBASE-4377:
---------------------------------------
@Todd,
I think there is some confusion. Clients do not directly access hdfs. Let me
add more detail.
In trunk post HBASE-451, the HMaster reads and caches data from the file system
(not the client). It then serves this the HTableDescriptors to the client
rpc's via HConnectionManager to talk to the HMaster which just ships the
cached HTD data.
HMaster on initialization reads file system for HTD data.
Client calls listTables() -> HMaster (serve cached data from file system).
Pre-HBASE-451, it the client HConnectionManager does a meta scan and builds
HTableDescriptors.
Client calls listTables() which actually is a metascan and that builds htds.
> [hbck] Offline rebuild .META. from fs data only.
> ------------------------------------------------
>
> Key: HBASE-4377
> URL: https://issues.apache.org/jira/browse/HBASE-4377
> Project: HBase
> Issue Type: New Feature
> Reporter: Jonathan Hsieh
> Assignee: Jonathan Hsieh
> Attachments:
> 0001-HBASE-4377-hbck-Offline-rebuild-.META.-from-fs-data-.patch,
> hbase-4377-trunk.v2.patch
>
>
> In a worst case situation, it may be helpful to have an offline .META.
> rebuilder that just looks at the file system's .regioninfos and rebuilds meta
> from scratch. Users could move bad regions out until there is a clean
> rebuild.
> It would likely fill in region split holes. Follow on work could given
> options to merge or select regions that overlap, or do online rebuilds.
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