How to resolve : caught exception: No active NameNode was found

[#1]

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

/var/lib/ambari-server/resources/common-services/HDFS/vXXXX/package/scripts/hdfs_namenode.py

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