当名称节点失败时会发生什么情况，哪个进程将监视名称节点的心跳状态？ [英] what happens when name node fails, which process will monitor name node heart beat status?

问题描述

名称节点将具有所有数据节点信息，名称节点与所有数据节点交互作为其活动状态，如果有任何数据节点关闭，名称节点将开始使用与其他数据节点相同的任务。我的问题是，如果名称节点自失败？谁会看名字节点活动状态（Heart Beat）？

解决方案

在Hadoop 2.0.0之前，NameNode是单点在HDFS集群中发生故障（SPOF）。每个集群都有一个NameNode，如果该机器或进程不可用，整个集群将不可用，直到NameNode重新启动或在单独的机器上启动。

然而，在hadoop 2.0中，我们有了一项名为HDFS高可用性的新功能。我们可以在其中配置活动名称节点和备用名称节点。

请看下面的图表。

Name node will have all the data nodes information, Name node interacts with all data nodes for its active state, if any data node does down, name node will start using the same task with other data nodes. My question here is what if name node it self fails? who will watch name node active state (Heart Beat) ?

解决方案

Prior to Hadoop 2.0.0, the NameNode was a single point of failure (SPOF) in an HDFS cluster. Each cluster had a single NameNode, and if that machine or process became unavailable, the cluster as a whole would be unavailable until the NameNode was either restarted or brought up on a separate machine.

There is no automatic recovery or no system to monitor the name node failure.

However, in the hadoop 2.0, we have new feature called HDFS High availability. Where we can configure active name node and standby name node.

Have a look at the below diagram.

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