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Symtoms :

NameNode HA states: active_namenodes =[], standby_namenodes =[], unknown_namenodes =[(u'nn1',

Solution :

Could be in order :

1) Ambari is doing the timeout ( 5 sec is default ) and killing the process if the NN takes long to start you can change the value of the timeout in


From this:

@retry(times=5, sleep_time=5, backoff_factor=2, err_class=Fail)

To this:

@retry(times=25, sleep_time=25, backoff_factor=2, err_class=Fail)

if not enough to this:

@retry(times=50, sleep_time=25, backoff_factor=2, err_class=Fail)

2) Could be the Zookeeper not getting the status of the NN

for this you can try

  1. Restart zookeeper, if it's still not working , then try the following
  2. Check the content of the Znode ( hadoop-ha ), save the namespace of the NN and delete the content and restart the NN
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