Hi Leena, Do you have a firewall between the two DCs? If yes, "connection reset" can be caused by Cassandra trying to use a TCP connection which is already closed by the firewall. Please make sure that you set high connection timeout at firewall. Also, make sure your servers are not overloaded. Please see https://developer.ibm.com/answers/questions/231996/why-do-we-get-the-error-connection-reset-by-peer-d.html
for general causes of connection reset. Also, as I told earlier, Cassandra troubleshooting explains it well https://docs.datastax.com/en/cassandra/2.0/cassandra/troubleshooting/trblshootIdleFirewall.html . Make sure firewall and node tcp settings are in sync such that nodes close a tcp connection before firewall does that. With firewall timeout, we generally see merkle tree request/response failing between nodes in two DCs and then repair is hung for ever. Not sure how merkle tree creation which is node specific would get impacted by multi dc setup. Are repairs with -local options completing without problems? Thanks Anuj
