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From dlmarion <dlmar...@hotmail.com>
Subject RE: HA NN Failover question
Date Sat, 15 Mar 2014 01:29:00 GMT
Server 1: NN1 and ZKFC1

Server 2: NN2 and ZKFC2

Server 3: Journal1 and ZK1

Server 4: Journal2 and ZK2

Server 5: Journal3 and ZK3

Server 6+: Datanode


All in the same rack. I would expect the ZKFC from the active name node server to lose its
lock and the other ZKFC to tell the standby namenode that it should become active (I’m assuming
that’s how it works).


- Dave


From: Juan Carlos [mailto:jucaf1@gmail.com] 
Sent: Friday, March 14, 2014 9:12 PM
To: user@hadoop.apache.org
Subject: Re: HA NN Failover question


Hi Dave,

How many zookeeper servers do you have and where are them? 

Juan Carlos Fernández Rodríguez

El 15/03/2014, a las 01:21, dlmarion <dlmarion@hotmail.com> escribió:

I was doing some testing with HA NN today. I set up two NN with active failover (ZKFC) using
sshfence. I tested that its working on both NN by doing ‘kill -9 <pid>’ on the active
NN. When I did this on the active node, the standby would become the active and everything
seemed to work. Next, I logged onto the active NN and did a ‘service network stop’ to
simulate a NIC/network failure. The standby did not become the active in this scenario. In
fact, it remained in standby mode and complained in the log that it could not communicate
with (what was) the active NN. I was unable to find anything relevant via searches in Google
in Jira. Does anyone have experience successfully testing this? I’m hoping that it is just
a configuration problem.


FWIW, when the network was restarted on the active NN, it failed over almost immediately.





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