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https://issues.apache.org/jira/browse/HBASE-10319?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13935016#comment-13935016
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Himanshu Vashishtha commented on HBASE-10319:
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bq. having hbase periodically force a log roll. This would enable the hdfs dn
con complete.
A roll creates a new file, writes and sync its header, and then closes the old
writer. I wonder how it solve the original issue because you would still have
one open file ?
I guess decommissioning blacklists a DN, so when a new file is created, NN
ensures no blocks are allocated on this DN. Just want to confirm.
> HLog should roll periodically to allow DN decommission to eventually complete.
> ------------------------------------------------------------------------------
>
> Key: HBASE-10319
> URL: https://issues.apache.org/jira/browse/HBASE-10319
> Project: HBase
> Issue Type: Bug
> Reporter: Jonathan Hsieh
> Assignee: Matteo Bertozzi
> Fix For: 0.98.0, 0.96.2, 0.94.17
>
> Attachments: HBASE-10319-v0.patch, HBASE-10319-v1.patch
>
>
> We encountered a situation where we had an esseitially read only table and
> attempted to do a clean HDFS DN decommission. DN's cannot decomission if
> there are open blocks being written to currently on it. Because the hbase
> Hlog file was open, had some data (hlog header), the DN could not
> decommission itself. Since no new data is ever written, the existing
> periodic check is not activated.
> After discussing with [~atm], it seems that although an hdfs semantics change
> would be ideal (e.g. hbase doesn't have to be aware of hdfs decommission and
> the client would roll over) this would take much more effort than having
> hbase periodically force a log roll. This would enable the hdfs dn con
> complete.
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