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NameNode

  • The NameNode executes file system namespace operations like opening, closing, and renaming files and directories.It also determines the mapping of blocks to DataNodes.

DataNodes

  • The DataNodes are responsible for serving read and write requests from the file system’s clients. The DataNodes also perform block creation, deletion, and replication upon instruction from the NameNode.
  • The DataNode stores HDFS data in files in its local file system.The DataNode has no knowledge about HDFS files. It stores each block of HDFS data in a separate file in its local file system.

File

  • a file is split into one or more blocks and these blocks are stored in a set of DataNodes.

  • all blocks in a file except the last block are the same size.

  • Files in HDFS are write-once and have strictly one writer at any time.

The Persistence of File System Metadata

  • The NameNode uses a transaction log called the EditLog to persistently record every change that occurs to file system metadata.
  • The entire file system namespace, including the mapping of blocks to files and file system properties, is stored in a file called the FsImage. The FsImage is stored as a file in the NameNode’s local file system too.

Blockreport: DataNode scans through its local file system, generates a list of all HDFS data blocks that correspond to each of these local files and sends this report to the NameNode

源码

2.7.3源码

  • 编译问题
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问题：Failed to parse plugin descriptor for org.apache.hadoop:hadoop-maven-plugins

解决：cd到hadoop-maven-plugins，执行mvn clean 然后 install 一下，再执行编译通过

端口

HDFS

DataNode

 50010  dfs.datanode.address   datanode服务端口，用于数据传输
50075  dfs.datanode.http.address  http服务的端口
50475  dfs.datanode.https.address  https服务的端口
50020  dfs.datanode.ipc.address   ipc服务的端口

NameNode

​ 50070 dfs.namenode.http-address http服务的端口 （访问hadoop的管理页面）
​ 50470 dfs.namenode.https-address https服务的端口
​ 8020 fs.defaultFS 接收Client连接的RPC端口，用于获取文件系统metadata信息。

journalnode

 8485   dfs.journalnode.rpc-address   RPC服务
 8480   dfs.journalnode.http-address   HTTP服务

ZKFC

 8019   dfs.ha.zkfc.port   ZooKeeper FailoverController，用于NN HA

YARN

ResourceManager

8032  yarn.resourcemanager.address   RM的applications manager(ASM)端口
8030  yarn.resourcemanager.scheduler.address  scheduler组件的IPC端口
8031  yarn.resourcemanager.resource-tracker.address  IPC
8033  yarn.resourcemanager.admin.address  IPC
8088  yarn.resourcemanager.webapp.address   http服务端口（**访问yarn的管理页面**）

NodeManager

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8040  yarn.nodemanager.localizer.address  localizer IPC
8042  yarn.nodemanager.webapp.address   http服务端口（**从节点node管理界面，可查看节点的任务处理信息**）
8041  yarn.nodemanager.address   NM中container manager的端口

JobHistory Server

10020   mapreduce.jobhistory.address   IPC
19888   mapreduce.jobhistory.webapp.address   http服务端口

HBase

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Master
    60000   hbase.master.port  IPC
    60010   hbase.master.info.port  http服务端口
RegionServer
    60020   hbase.regionserver.port   IPC
    60030   hbase.regionserver.info.port   http服务端口
HQuorumPeer
    2181  hbase.zookeeper.property.clientPort   HBase-managed ZK mode，使用独立的ZooKeeper集群则不会启用该端口。
    2888  hbase.zookeeper.peerport   HBase-managed ZK mode，使用独立的ZooKeeper集群则不会启用该端口。
    3888  hbase.zookeeper.leaderport  HBase-managed ZK mode，使用独立的ZooKeeper集群则不会启用该端口。

Hive

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Metastore
     9083  /etc/default/hive-metastore中export PORT=<port>来更新默认端口   
HiveServer
     10000   /etc/hive/conf/hive-env.sh中export HIVE_SERVER2_THRIFT_PORT=<port>来更新默认端口

ZooKeeper

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Server
     2181  /etc/zookeeper/conf/zoo.cfg中clientPort=<port>  对客户端提供服务的端口
     2888  /etc/zookeeper/conf/zoo.cfg中server.x=[hostname]:nnnnn[:nnnnn]，标蓝部分  follower用来连接到leader，只在leader上监听该端口。
     3888  /etc/zookeeper/conf/zoo.cfg中server.x=[hostname]:nnnnn[:nnnnn]，标蓝部分  用于leader选举的。只在electionAlg是1,2或3(默认)时需要。