How to run ray tune on two server?

Ray Core
1

Hi,
My ray version is 1.9.0

I have encountered similar issue with this one: How to run tune on multiple machines? · Issue #9931 · ray-project/ray · GitHub

I ran ray start --head on server A. It pops out following message:

Local node IP: 192.168.173.153

--------------------
Ray runtime started.
--------------------

Next steps
  To connect to this Ray runtime from another node, run
    ray start --address='192.168.173.153:6379' --redis-password='5241590000000000'
  
  Alternatively, use the following Python code:
    import ray
    ray.init(address='auto', _redis_password='5241590000000000')
  
  To connect to this Ray runtime from outside of the cluster, for example to
  connect to a remote cluster from your laptop directly, use the following
  Python code:
    import ray
    ray.init(address='ray://<head_node_ip_address>:10001')
  
  If connection fails, check your firewall settings and network configuration.
  
  To terminate the Ray runtime, run
    ray stop

which works fine.
But when I run ray start --address='192.168.173.153:6379' --redis-password='5241590000000000' on server B, it throws:

RuntimeError: Unable to connect to Redis at 192.168.173.153:6379 after 16 retries. Check that 192.168.173.153:6379 is reachable from this machine. If it is not, your firewall may be blocking this port. If the problem is a flaky connection, try setting the environment variable `RAY_START_REDIS_WAIT_RETRIES` to increase the number of attempts to ping the Redis server.

I try to ssh server A via ssh 192.168.173.153 on server B it working properly.

2

Perhaps 6379 is not an open port on server A?

3

I think there is a firewall problem:

I run nc -zv 192.168.173.153 on Server B and it says Ncat: No route to host.
but when I ping 192.168.173.153, it works fine:

PING 192.168.173.153 (192.168.173.153) 56(84) bytes of data.
64 bytes from 192.168.173.153: icmp_seq=1 ttl=64 time=0.132 ms
64 bytes from 192.168.173.153: icmp_seq=2 ttl=64 time=0.165 ms
64 bytes from 192.168.173.153: icmp_seq=3 ttl=64 time=0.106 ms
64 bytes from 192.168.173.153: icmp_seq=4 ttl=64 time=0.166 ms
64 bytes from 192.168.173.153: icmp_seq=5 ttl=64 time=0.134 ms
64 bytes from 192.168.173.153: icmp_seq=6 ttl=64 time=0.120 ms
64 bytes from 192.168.173.153: icmp_seq=7 ttl=64 time=0.115 ms
64 bytes from 192.168.173.153: icmp_seq=8 ttl=64 time=0.117 ms
64 bytes from 192.168.173.153: icmp_seq=9 ttl=64 time=0.104 ms
64 bytes from 192.168.173.153: icmp_seq=10 ttl=64 time=0.132 ms
64 bytes from 192.168.173.153: icmp_seq=11 ttl=64 time=0.126 ms
64 bytes from 192.168.173.153: icmp_seq=12 ttl=64 time=0.122 ms
^C
--- 192.168.173.153 ping statistics ---
12 packets transmitted, 12 received, 0% packet loss, time 11005ms
rtt min/avg/max/mdev = 0.104/0.128/0.166/0.020 ms

Also ssh 192.168.173.153 works.