FAQ
Hi,



Please help me in confirming the behavior of BNN when it is performing
checkPoint.



Scenario:

=======

1)Start Namenode.and BackupNameNode

2)Start writing files to HDFS continuously ....Say after 5 min
BackupNameNode is invoking doCheckpoint . then following exception is thrown
at BNN side



Exception:

========

error:java.io.IOException:java.lang.IllegalStateException:!!! WARNING !!!
File system changes are not persistent .No journal streams

at
org.apachel.hadoop.hdfs.server.namenode.FSEditLog.logEdit(FSEditLog.java:157
0)



Please find my Analysis for the above exception:

===================================

-->While checkpointing BNN will call startCheckpoint on namenode and it
will get NamenodeCommand

then saveCheckpoint is called at BNN as part of this it will clear the
editStreams in order to rename current dir to latestcheckpoint.tmp ,some
operations are performed on BNN like renaming current dir to
latestcheckpoint.tmp ...etc ..then it will populate the editStreams



At this time if any dfsclient is trying to write data to hdfs the above
exception is thrown .





PLEASE LET ME KNOW ABOUT THIS BEHAVIOUR ,AND HOW THE ABOVE EXCEPTION CAN BE
HANDLED



Thanks&Regards

sandeep







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groupcommon-user @
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postedFeb 8, '11 at 2:57p
activeFeb 8, '11 at 2:57p
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