NoHostAvailableException: All host(s) tried for query failed (no host was tried)

问题

We recently (this week) upgraded our java driver from 2.0.4 to 2.1.4 (we are running Cassandra version 2.0.12). We were using 2.0.4 for a long time (more than an year) in production and did not have this issue. But, after upgrading we starting seeing intermittent NoHostAvailableExceptions (that fail all the requests on client side):

Caused by: com.datastax.driver.core.exceptions.NoHostAvailableException: All host(s) tried for query failed (no host was tried)
    at com.datastax.driver.core.RequestHandler.sendRequest(RequestHandler.java:108) ~[stormjar.jar:na]
    at com.datastax.driver.core.SessionManager.execute(SessionManager.java:530) ~[stormjar.jar:na]
    at com.datastax.driver.core.SessionManager.executeQuery(SessionManager.java:566) ~[stormjar.jar:na]
    at com.datastax.driver.core.SessionManager.executeAsync(SessionManager.java:119) ~[stormjar.jar:na]

We are having this issue in production, so would love to get some advice on how to triage this. What we know for sure: * When errors start happening Cassandra cluster isn't under unusual load. * We are able to reach Cassandra hosts (cluster) from client side - Not a connection issue.

Cheers, -Ankush

来源：https://stackoverflow.com/questions/28770889/nohostavailableexception-all-hosts-tried-for-query-failed-no-host-was-tried