This is probably not the best place to ask such questions as they are not specifically related to Ambari but HDFS.
There are lots of scenarios when a NN can switch, and there is always a good reason for that :) Some of them can be: - if you're running a older version of hadoop/hdp (2.1), slow block reports or slow fsimage transfer can lead to NN switch, - you rpc pool is too small (NN server thread) - you're hit by the futex lock bug ( https://groups.google.com/forum/#!topic/mechanical-sympathy/QbmpZxp6C64) and might to upgrade your kernel(s). 2015-07-23 17:51 GMT+02:00 Loïc Chanel <[email protected]>: > Hi, > > I am using a high-availability cluster with 3 JournalNodes and 2 NameNodes > on 2 out of 3 of these hosts, and the NameNode switched his host 3 times in > less than 24 hours without apparent reason. > > This can't be a network problem, as the logs indicate clearly that the > NameNode can't send logs to the JournalNode running on the exact same host, > while calling it using its IP, and this doesn't seem to be a CPU or RAM > problem as the command sar does not return any abnormality, and Ganglia > graphics show that the JVM has way more memory than it needs to have. > > Do any of you have an idea about where the problem might come from ? > Thanks in advance, > > > Loïc > > Loïc CHANEL > Engineering student at TELECOM Nancy > Trainee at Worldline - Villeurbanne >
