[jira] [Updated] (HDFS-6827) Both NameNodes could be in STANDBY State due to HealthMonitor not aware of the target's status changing sometimes

["Liang Xie (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HDFS-6827?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Liang Xie updated HDFS-6827:
----------------------------

    Summary: Both NameNodes could be in STANDBY State due to HealthMonitor not aware of the target's status changing sometimes  (was: NameNode double standby)

> Both NameNodes could be in STANDBY State due to HealthMonitor not aware of the target's status changing sometimes
> -----------------------------------------------------------------------------------------------------------------
>
>                 Key: HDFS-6827
>                 URL: https://issues.apache.org/jira/browse/HDFS-6827
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: ha
>    Affects Versions: 2.4.1
>            Reporter: Zesheng Wu
>            Assignee: Zesheng Wu
>            Priority: Critical
>         Attachments: HDFS-6827.1.patch
>
>
> In our production cluster, we encounter a scenario like this: ANN crashed due to write journal timeout, and was restarted by the watchdog automatically, but after restarting both of the NNs are standby.
> Following is the logs of the scenario:
> # NN1 is down due to write journal timeout:
> {color:red}2014-08-03,23:02:02,219{color} INFO org.apache.hadoop.hdfs.server.namenode.NameNode: SHUTDOWN_MSG
> # ZKFC1 detected "connection reset by peer"
> {color:red}2014-08-03,23:02:02,560{color} ERROR org.apache.hadoop.security.UserGroupInformation: PriviledgedActionException as:xx@xx.HADOOP (auth:KERBEROS) cause:java.io.IOException: {color:red}Connection reset by peer{color}
> # NN1 wat restarted successfully by the watchdog:
> 2014-08-03,23:02:07,884 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: Web-server up at: xx:13201
> 2014-08-03,23:02:07,884 INFO org.apache.hadoop.ipc.Server: IPC Server Responder: starting
> {color:red}2014-08-03,23:02:07,884{color} INFO org.apache.hadoop.ipc.Server: IPC Server listener on 13200: starting
> 2014-08-03,23:02:08,742 INFO org.apache.hadoop.ipc.Server: RPC server clean thread started!
> 2014-08-03,23:02:08,743 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: Registered DFSClientInformation MBean
> 2014-08-03,23:02:08,744 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: NameNode up at: xx/xx:13200
> 2014-08-03,23:02:08,744 INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem: Starting services required for standby state
> # ZKFC1 retried the connection and considered NN1 was healthy
> {color:red}2014-08-03,23:02:08,292{color} INFO org.apache.hadoop.ipc.Client: Retrying connect to server: xx/xx:13200. Already tried 0 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=1, sleepTime=1 SECONDS)
> # ZKFC1 still considered NN1 as a healthy Active NN, and didn't trigger the failover, as a result, both NNs were standby.
> The root cause of this bug is that NN is restarted too quickly and ZKFC health monitor doesn't realize that.



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