Cannot start Cassandra : Port already in use - cassandra

Question

I have two Ubuntu 16.04 nodes on which I installed Cassandra 3.11.3 with java version "1.8.0_181". I want to merge these two nodes into a Cassandra cluster. Their intern ips are 172.16.10.20 and 172.16.10.30.
on each /etc/cassandra/cassandra.yaml file I modified the following lines:
cluster_name: 'my_cluster'
- seeds: "172.16.10.20,172.16.10.30"
listen_address: XXXX
rpc_address: XXXX
where XXXX is respectively the intern ip of the current node.
I then restart Cassandra on each node
sudo service cassandra restart
and check that Cassandra runs :
sudo service cassandra status
cassandra.service - LSB: distributed storage system for structured data
Loaded: loaded (/etc/init.d/cassandra; generated)
Active: active (running) since Wed 2018-08-08 00:31:42 UTC; 3s ago
Docs: man:systemd-sysv-generator(8)
and the cluster
nodetool status
Datacenter: dc1
===============
Status=Up/Down
|/ State=Normal/Leaving/Joining/Moving
-- Address Load Tokens Owns (effective) Host ID Rack
UN 172.16.10.20 190.11 KiB 256 100.0% 84dded4c-c74e-45f4-9481-ff837fec229d rack1
UN 172.16.10.30 265.06 KiB 256 100.0% 4695fef4-70c7-46b2-a0bd-8b752fe5beb6 rack1
Everything is up and normal.
I want to connect now to Cassandra:
cqlsh
and get:
Connection error: ('Unable to connect to any servers', {'127.0.0.1': error(111, "Tried connecting to [('127.0.0.1', 9042)]. Last error: Connection refused")})
Some googling later, I want to start cassandra by hand
cassandra
and get (among a huge message):
ERROR [main] 2018-08-07 23:02:51,365 CassandraDaemon.java:708 - Port already in use: 7199; nested exception is:
java.net.BindException: Address already in use (Bind failed)
It looks like the port 7199 is already in use. I kill the corresponding pid, change in /etc/cassandra/cassandra-env.sh the JMX_PORT to 7200... same issue, the port is said to be in use, plus the error
00:33:06,236 |-ERROR in ch.qos.logback.core.rolling.RollingFileAppender[SYSTEMLOG] - openFile(/var/log/cassandra/system.log,true) call failed. java.io.FileNotFoundException: /var/log/cassandra/system.log (Permission denied)
I have changed the permission, but the error remains. At this point of the story I am running out of ideas. What I am trying to achieve seem pretty straighforward so I guess others must have run into a similar issue.

Answer 1

The nodetool status output says it all here. You had everything running just fine. So revert any changes in terms of port usage.
As your nodetool status reveals that your node IPs are 172.16.10.20 and 172.16.10.30, try running cqlsh and providing one of those IPs. cqlsh tries to connect to 127.0.0.1 by default, which will not work in a plural node cluster.
cqlsh 172.16.10.20 -u yourusername -p yourpassword
Note: You can omit -u and -p if you don't have auth enabled. But if that's true, then you should really change your cluster to enable auth.