（十二）大数据实战——hadoop集群之HDFS高可用自动故障转移

前言

本节内容主要介绍一下hadoop集群下实现HDFS高可用的自动故障转移，HDFS高可用的自动故障转移主要通过zookeeper实现故障的监控和主节点的切换。自动故障转移为 HDFS 部署增加了两个新组件：ZooKeeper 和 ZKFailoverController （ZKFC）进程。ZooKeeper 是维护少量协调数据，通知客户端这些数据的改变和监视客户端故障的高可用服务。在开始本节内容之前，我们需要提前安装好zookeeper集群，可参考作者往期博客内容。

正文

• 集群规划

|-------------|-------------|-------------|
| hadoop101 | hadoop102 | hadoop103 |
| NameNode | NameNode | NameNode |
| JournalNode | JournalNode | JournalNode |
| DataNode | DataNode | DataNode |
| Zookeeper | Zookeeper | Zookeeper |
| ZKFC | ZKFC | ZKF |
[hadoop集群高可用hdfs]

• 在core-site.xml文件中增加zkfc要连接的zkServer地址

• core-site.xml配置

  <?xml version="1.0" encoding="UTF-8"?> <?xml-stylesheet type="text/xsl" href="configuration.xsl"?>

    http://www.apache.org/licenses/LICENSE-2.0
  
  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License. See accompanying LICENSE file.
  

  -->

  <configuration>

    <!-- 把多个 NameNode 的地址组装成一个集群 mycluster -->
    <property>
        <name>fs.defaultFS</name>
        <value>hdfs://mycluster</value>
    </property>
  
    <!-- 指定hadoop数据的存储目录 -->
    <property>
        <name>hadoop.tmp.dir</name>
        <value>/opt/module/hadoop-3.1.3/data</value>
    </property>
  
    <!-- 配置HDFS网页登录使用的静态用户为hadoop -->
    <property>
        <name>hadoop.http.staticuser.user</name>
        <value>hadoop</value>
    </property>
  
    <!-- 指定 zkfc 要连接的 zkServer 地址 -->
    <property>
        <name>ha.zookeeper.quorum</name>
        <value>hadoop101:2181,hadoop102:2181,hadoop103:2181</value>
    </property>
  

  </configuration>

• 在hdfs-site.xml中增加故障转移的配置

• hdfs-site.xml配置

  <?xml version="1.0" encoding="UTF-8"?> <?xml-stylesheet type="text/xsl" href="configuration.xsl"?>

    http://www.apache.org/licenses/LICENSE-2.0
  
  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License. See accompanying LICENSE file.
  

  -->

  <configuration> <property> <name>dfs.namenode.name.dir</name> <value>file://${hadoop.tmp.dir}/nn</value> </property> <property> <name>dfs.datanode.data.dir</name> <value>file://${hadoop.tmp.dir}/dn</value> </property> <property> <name>dfs.journalnode.edits.dir</name> <value>${hadoop.tmp.dir}/jn</value> </property> <property> <name>dfs.nameservices</name> <value>mycluster</value> </property> <property> <name>dfs.ha.namenodes.mycluster</name> <value>nn1,nn2,nn3</value> </property> <property> <name>dfs.namenode.rpc-address.mycluster.nn1</name> <value>hadoop101:8020</value> </property> <property> <name>dfs.namenode.rpc-address.mycluster.nn2</name> <value>hadoop102:8020</value> </property> <property> <name>dfs.namenode.rpc-address.mycluster.nn3</name> <value>hadoop103:8020</value> </property> <property> <name>dfs.namenode.http-address.mycluster.nn1</name> <value>hadoop101:9870</value> </property> <property> <name>dfs.namenode.http-address.mycluster.nn2</name> <value>hadoop102:9870</value> </property> <property> <name>dfs.namenode.http-address.mycluster.nn3</name> <value>hadoop103:9870</value> </property> <property> <name>dfs.namenode.shared.edits.dir</name> <value>qjournal://hadoop101:8485;hadoop102:8485;hadoop103:8485/mycluster</value> </property> <property> <name>dfs.client.failover.proxy.provider.mycluster</name> <value>org.apache.hadoop.hdfs.server.namenode.ha.ConfiguredFailoverProxyProvider</value> </property> <property> <name>dfs.ha.fencing.methods</name> <value>sshfence</value> </property> <property> <name>dfs.ha.fencing.ssh.private-key-files</name> <value>/home/hadoop/.ssh/id_rsa</value> </property>

    <!-- 启用 nn 故障自动转移 -->
    <property>
        <name>dfs.ha.automatic-failover.enabled</name>
        <value>true</value>
    </property>
  

  </configuration>

• 使用hsync分发修改的配置文件

• 启动zookeeper集群

• 启动 Zookeeper集群后，然后再初始化HA在Zookeeper集群中状态

命令：hdfs zkfc -formatZK

• 启动HDFS服务

• 命令：start-dfs.sh

• 关闭hadoop102的active的节点，查看故障是否会转移

• 当前激活的节点是hadoop102

• 关闭hadoop102的namenode节点

• 发现故障并未转移，每个服务需要独立安装psmisc，实现服务通信，命令：yum install psmisc -y

- 当前激活节点变为hadoop103，hadoop101为备用节点，hadoop102无法访问，实现了故障转移

结语

关于hadoop集群之HDFS高可用自动故障转移的内容到这里就结束了，我们下期见。。。。。。