Cassandra集群的一个主机倒塌了。在那个小时窗口中，应用程序日志中会抛出这些回溯。密钥空间RF和一致性级别配置为我们应该能够处理一个节点丢失。
这些追溯的原因是什么？ 可以忽略这些吗？
卡桑德拉-蟒== 2.6.0
Traceback (most recent call last):
File \"/opt/aruba/central/apps/monitoring/ENV/local/lib/python2.7/site-packages/cassandra/cluster.py\", line 1820, in run_add_or_renew_pool
new_pool = HostConnection(host, distance, self)
File \"/opt/aruba/central/apps/monitoring/ENV/local/lib/python2.7/site-packages/cassandra/pool.py\", line 294, in __init__
self._connection = session.cluster.connection_factory(host.address)
File \"/opt/aruba/central/apps/monitoring/ENV/local/lib/python2.7/site-packages/cassandra/cluster.py\", line 784, in connection_factory
return self.connection_class.factory(address, self.connect_timeout, *args, **kwargs)
File \"/opt/aruba/central/apps/monitoring/ENV/local/lib/python2.7/site-packages/cassandra/connection.py\", line 260, in factory
conn = cls(host, *args, **kwargs)
File \"/opt/aruba/central/apps/monitoring/ENV/local/lib/python2.7/site-packages/cassandra/io/asyncorereactor.py\", line 167, in __init__
self._connect_socket()
File \"/opt/aruba/central/apps/monitoring/ENV/local/lib/python2.7/site-packages/cassandra/connection.py\", line 293, in _connect_socket
raise socket.error(sockerr.errno,
\"Tried connecting to %s. Last error: %s\" % ([a[4] for a in addresses], sockerr.strerror))
error: [Errno None] Tried connecting to [(\\'172.20.111.22\\', 9042)]. Last error: None