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https://issues.apache.org/jira/browse/HBASE-2234?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12849926#action_12849926
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Jean-Daniel Cryans commented on HBASE-2234:
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I saw a minor issue with this patch, if HBase doesn't have hdfs-site.xml in its
CP or isn't configured with the same dfs.replication, this call will not return
the right value:
{code}
+ numCurrentReplicas < fs.getDefaultReplication()) {
{code}
For example, I was testing HBASE-2337 on a single node and didn't put hadoop's
conf dir in HBase's CP but did configure rep=1, I ended up rolling the logs for
every edit:
{code}
WARN org.apache.hadoop.hbase.regionserver.HLog: HDFS pipeline error detected.
Found 1 replicas but expecting 3 replicas. Requesting close of hlog.
WARN org.apache.hadoop.hbase.regionserver.HLog: HDFS pipeline error detected.
Found 1 replicas but expecting 3 replicas. Requesting close of hlog.
WARN org.apache.hadoop.hbase.regionserver.HLog: HDFS pipeline error detected.
Found 1 replicas but expecting 3 replicas. Requesting close of hlog.
...
{code}
I can see hordes of new users coming with the same issue. Is there a better way
to ask HDFS about the default replication setting and store it?
> Roll Hlog if any datanode in the write pipeline dies
> ----------------------------------------------------
>
> Key: HBASE-2234
> URL: https://issues.apache.org/jira/browse/HBASE-2234
> Project: Hadoop HBase
> Issue Type: Improvement
> Components: regionserver
> Reporter: dhruba borthakur
> Assignee: Nicolas Spiegelberg
> Priority: Blocker
> Fix For: 0.20.4
>
> Attachments: HBASE-2234-20.4-1.patch, HBASE-2234-20.4.patch
>
>
> HDFS does not replicate the last block of a file that is being written to.
> This means that is datanodes in the write pipeline die, then the data blocks
> in the transaction log would be experiencing reduced redundancy. It would be
> good if the region server can detect datanode-death in the write pipeline
> while writing to the transaction log and if this happens, close the current
> log an open a new one. This depends on HDFS-826
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