Regionserver is not getting started on one of the datanode in 9 node cluster.

[#1]

I have installed Apache Ambari 2.0.0 using HDP distribution. i have 9 node in HA cluster in which 6 is datanodes and other are master node. version of hadoop is 2.6.0 and version of hbase is 0.98.4. i have changed one configuration in hbase-site.xml in ambari(changed HBase Client Maximum key-value Size from 10485760 to 20485760). when i restarting hbase, it is taking too long to respond(around 50 minutes) in ambari and finally getting failed. i tried to restart regionserver manually one by one. it started regionserver successfully on all the slaves except one. surprisingly this particular regionserver is not even getting stopped through ambari. please help! how can i restart hbase sucessfully?

[#2]

Great, I escalated your request, someone will contact you

[#3]

Thanks Artem.