in ambari there is alert regarding 1 missing block from 6 days.
but when i check using " hdfs fsck / " its showing there is not any missing block.
is this bug in ambari ?
What do you see when you hit the following NameNode JMX call from Ambari Server host?
# curl -s "http://$ACTIVE_NAMENODE:50070/jmx?qry=Hadoop:service=NameNode,name=FSNamesystem" | grep 'MissingBlocks'
# curl -s "http://$STANDBY_NAMENODE:50070/jmx?qry=Hadoop:service=NameNode,name=FSNamesystem" | grep 'MissingBlocks'
What is the Ambari Version are you using?
Can you try opening ambari UI in Incognito Mode (Private Mode) in the Web Browser just to see if the browser cache is not playing any role there?
If fsck results contain missing block with "corrupt" , you'd better run fsck with more options.
hdfs fsck [corrupted path] -files -locations -blocks