Yang Jiandan created HDFS-12132:
-----------------------------------

             Summary: Both two NameNodes become Standby because the ZKFC 
exception
                 Key: HDFS-12132
                 URL: https://issues.apache.org/jira/browse/HDFS-12132
             Project: Hadoop HDFS
          Issue Type: Bug
          Components: auto-failover
    Affects Versions: 2.8.1
            Reporter: Yang Jiandan


Both two NameNodes become Standby because the ZKFC exception When rolling 
upgrading Hadoop from Hadoop-2.6.5 to Hadoop-2.8.0, this lead HDFS to be not 
available. The logic of processing exception in ZKFC seems to be problematic, 
ZKFC should guarantee to have a active NameNode.

Before upgrading, the cluster was deployed with HA, NN1 was active, and NN2 was 
standby
The configuration before upgrading is as follows:

{code:java}
dfs.namenode.rpc-address.nameservice.nn1 nn1: 8020
dfs.namenode.rpc-address.nameservice.nn2 nn2: 8020
{code}

After upgrading, add the configuration of the separate RPC service:
{code:java}
dfs.namenode.rpc-address.nameservice.nn1 nn1: 8020
dfs.namenode.rpc-address.nameservice.nn2 nn2: 8020
dfs.namenode.servicerpc-address.nameservice.nn1 nn1: 8021
dfs.namenode.servicerpc-address.nameservice.nn2 nn2: 8021
dfs.namenode.lifeline.rpc-address.nameservice.nn1 nn1: 8022
dfs.namenode.lifeline.rpc-address.nameservice.nn2 nn2: 8022
{code}

The upgrade steps are as follows:
1. Upgrade NN2: restart NameNode process on NN2
2. Upgrade NN1: restart the NameNode process on NN1, then NN2 becomes active, 
NN1 is standby
3. Restart both ZKFC on NN1 and NN2

After restarting ZKFC, Two ZKFC threw same exception and two NameNodes have 
become Standby, exception log is:

{code:java}
2017-07-11 18:49:44,311 WARN [main-EventThread] 
org.apache.hadoop.ha.ActiveStandbyElector: Exception handling the winning of 
election
java.lang.RuntimeException: Mismatched address stored in ZK for NameNode at 
nn2/xx.xxx.xx.xxx:8022: Stored protobuf was nameserviceId: “nameservice”
namenodeId: "nn2"
hostname: “nn2_hostname”
port: 8020
zkfcPort: 8019
, address from our own configuration for this NameNode was 
nn2_hostname/xx.xxx.xx.xxx:8021
        at 
org.apache.hadoop.hdfs.tools.DFSZKFailoverController.dataToTarget(DFSZKFailoverController.java:87)
        at 
org.apache.hadoop.ha.ZKFailoverController.fenceOldActive(ZKFailoverController.java:506)
        at 
org.apache.hadoop.ha.ZKFailoverController.access$1100(ZKFailoverController.java:61)
        at 
org.apache.hadoop.ha.ZKFailoverController$ElectorCallbacks.fenceOldActive(ZKFailoverController.java:895)
        at 
org.apache.hadoop.ha.ActiveStandbyElector.fenceOldActive(ActiveStandbyElector.java:985)
        at 
org.apache.hadoop.ha.ActiveStandbyElector.becomeActive(ActiveStandbyElector.java:882)
        at 
org.apache.hadoop.ha.ActiveStandbyElector.processResult(ActiveStandbyElector.java:467)
        at 
org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.java:599)
        at org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:498)
2017-07-11 18:49:44,311 INFO [main-EventThread] 
org.apache.hadoop.ha.ActiveStandbyElector: Trying to re-establish ZK session
2017-07-11 18:49:44,311 INFO [main-EventThread] org.apache.zookeeper.ZooKeeper: 
Session: 0x15c3ada0ec319aa closed
{code}



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