无法实现一致性级别ONE：info = {'required_replicas'：1，'alive_replicas'：0，'consistency'：1} [英] Cannot achieve consistency level ONE: info={ 'required_replicas': 1, 'alive_replicas': 0, 'consistency': 1}

问题描述

看起来在我的Cassandra设置中没有正确地执行键空间复制，我需要一些想法来解决这个问题。我已经配置了多数据中心集群，但是开始我已经设置keyspace使用SimpleStrategy与RF 3.

It looks like keyspace replication is not happening correctly in my Cassandra setup, I need some ideas in troubleshooting this. I have configured multi datacenter cluster but to begin with I have set the keyspace to use SimpleStrategy with RF 3.

列族存在：

cqlsh:kairosdb> select columnfamily_name from system.schema_columnfamilies where keyspace_name = 'kairosdb';

 columnfamily_name
-------------------
       data_points
     row_key_index
      string_index

(3 rows)

但我无法查询：

cqlsh:kairosdb> select count(*) from data_points limit 100000;
 Traceback (most recent call last):
  File "/usr/bin/cqlsh", line 957, in perform_simple_statement
    rows = self.session.execute(statement, trace=self.tracing_enabled)
  File "/usr/share/cassandra/lib/cassandra-driver-internal-only-2.1.1.post.zip/cassandra-driver-2.1.1.post/cassandra/cluster.py", line 1282, in execute
    result = future.result(timeout)
  File "/usr/share/cassandra/lib/cassandra-driver-internal-only-2.1.1.post.zip/cassandra-driver-2.1.1.post/cassandra/cluster.py", line 2776, in result
    raise self._final_exception
Unavailable: code=1000 [Unavailable exception] message="Cannot achieve consistency level ONE" info={'required_replicas': 1, 'alive_replicas': 0, 'consistency': 1}

1. 在种子列表中使用每个DC中的2个节点


2. 对Snitch使用org.apache.cassandra.locator.GossipingPropertyFileSnitch


3. 在cassandra-rackdc.properties中为节点指定不同的名称

以下是创建的键空间：

cqlsh:kairosdb> describe keyspace kairosdb;

CREATE KEYSPACE kairosdb WITH replication = {'class': 'SimpleStrategy', 'replication_factor': '3'}  AND durable_writes = true;

任何想法我可以做什么来解决这个问题？

Any ideas what I can do to troubleshoot this?

推荐答案

在您的键空间创建中，您有以下语法：

In your keyspace creation you have this syntax:

CREATE KEYSPACE kairosdb WITH replication = {'class': 'SimpleStrategy', 'replication_factor': '3'}  AND durable_writes = true;

NetworkTopologyStrategy ，例如：

CREATE KEYSPACE kairosdb WITH replication = {'class': 'NetworkTopologyStrategy', 'DC1': 3, 'DC2': 3};

按照以下文档链接使用 NetworkTopologyStrategy 当您拥有（或计划拥有）跨多个数据中心部署的群集...

As per the following documentation link, "Use NetworkTopologyStrategy when you have (or plan to have) your cluster deployed across multiple data centers..."

http://www.datastax.com/documentation/cassandra/2.0/cassandra/architecture/architectureDataDistributeReplication_c.html

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