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From "Jing Zhao (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-5869) When rolling upgrade is in progress, NN should only create checkpoint right before the upgrade marker
Date Thu, 06 Feb 2014 00:36:24 GMT

    [ https://issues.apache.org/jira/browse/HDFS-5869?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13892834#comment-13892834
] 

Jing Zhao commented on HDFS-5869:
---------------------------------

bq. we should disable the checkpointing from StandbyCheckpointer in StandbyNN when RollingUpgrade
in progress
Once we have HDFS-5889, we do not need to disable the checkpointing in SBN anymore.

For the following code:
{code}
+          if (totalEdits > 1) {
+            // save namespace if this is not the second edit transaction
+            // (the first must be OP_START_LOG_SEGMENT)
+            fsNamesys.getFSImage().saveNamespace(fsNamesys);
+          }
{code}
My understand is that: if we have successfully done the checkpoint for the startRollingUpgrade
call, we will have an fsimage and in case that this is the latest fsimage, we do not need
to do the checkpoint again while restarting. But if the fsimage is lost or this is the SBN/SNN,
this extra checkpoint can be triggered. Do I understand correctly here? And I guess the SecondaryNN
actually does not need to do this extra checkpoint? 


> When rolling upgrade is in progress, NN should only create checkpoint right before the
upgrade marker
> -----------------------------------------------------------------------------------------------------
>
>                 Key: HDFS-5869
>                 URL: https://issues.apache.org/jira/browse/HDFS-5869
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>          Components: namenode
>            Reporter: Tsz Wo (Nicholas), SZE
>            Assignee: Tsz Wo (Nicholas), SZE
>         Attachments: h5869_20140204.patch, h5869_20140204b.patch, h5869_20140205.patch
>
>
> - When starting rolling upgrade, NN should create a checkpoint before it writes the upgrade
marker edit log transaction.
> - When rolling upgrade is in progress, NN should reject saveNamespace rpc calls. Further,
if NN restarts, it should create a checkpoint only right before the upgrade marker.



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