HDFS-HA
HA（High Available），即高可用（7*24小时不中断服务）
单点故障即有一台机器挂了导致全部都挂了；HA就是解决单点故障，就是针对NameNode；
主Active：读写、从standby只读；所依赖的服务都必须是高可用的；
两种解决共享空间的方案：NFS、QJM（主流的）
奇数台机器；QJM跟zookeeper（数据全局一致；半数以上的机器存活就可以提供服务）高可用的方式一模一样，；
QJM也是基于Paxos算法，系统容错不能超过n-1/2， 5台容错2台；
这个架构只能手动决定哪个是active哪个是standby；必须只能有一个active！！如果出现两个NameNode，即两个都是active，它可能还不报错，那么可能会导致整个集群的数据都是错的，问题很严重！两个AA的情况叫脑裂（split brain缩写sb）。
standby要想变成active，要确保active那个，需要安全可靠的zookeeper（文件系统+通知机制）第三方来联系两方 ---> 实现故障的自动转移；
由Zkfc来联系zookeeper，并不是namenode直接联系，（zookeeper客户端）；HA是hadoop2.0才有的，namenode在1.0时就有了；没有把zkfc写进namenode是为了保持NameNode的健壮性，没有zkfc之前就已经运行的很好了（鲁棒性）；NameNode和Zkfc虽然是两个进程但它们是绑定到一起的。
两个zkfc怎么决定谁初始化就是active呢，谁快谁就是active； 是active状态它会在zookeeper中有一个临时节点，zkfc会尝试看看zookeeper中有没有这个临时节点，如果没有我就变成这个临时节点，成为active，慢的一看有了，就变成standby；
NameNode发生假死，zkfc就会把zookeeper中的临时节点删除，去通知另外一个namenode的zkfc，让它去成为active，这个namenode就会去强行杀死假死的namenode，防止脑裂！如果杀不死就自定义一个脚本强制它关机，成功之后才会变成active。
现在合并fsimage是由standby来完成的，没有secondaryNameNode；
在module目录下创建一个ha文件夹mkdir ha将/opt/module/下的 hadoop-2.7.2拷贝到/opt/module/ha目录下cp -r hadoop-2.7.2/ /opt/module/ha/删除data logs等文件
配置core-site.xml
fs.defaultFS hdfs://mycluster hadoop.tmp.dir /opt/module/ha/hadoop-2.7.2/data/tmp ha.zookeeper.quorum hadoop101:2181,hadoop102:2181,hadoop103:2181
配置hdfs-site.xml
dfs.nameservices mycluster dfs.ha.namenodes.mycluster nn1,nn2 dfs.namenode.rpc-address.mycluster.nn1 hadoop101:9000 dfs.namenode.rpc-address.mycluster.nn2 hadoop102:9000 dfs.namenode.http-address.mycluster.nn1 hadoop101:50070 dfs.namenode.http-address.mycluster.nn2 hadoop102:50070 dfs.namenode.shared.edits.dir qjournal://hadoop101:8485;hadoop102:8485;hadoop103:8485/mycluster dfs.ha.fencing.methods sshfence dfs.ha.fencing.ssh.private-key-files /home/kris/.ssh/id_rsa dfs.journalnode.edits.dir /opt/module/ha/hadoop-2.7.2/data/jn dfs.permissions.enable false dfs.client.failover.proxy.provider.mycluster org.apache.hadoop.hdfs.server.namenode.ha.ConfiguredFailoverProxyProvider dfs.ha.automatic-failover.enabled true
发送到其他机器xsync ha
启动HDFS-HA集群
1. 在各个JournalNode节点上，输入以下命令启动journalnode服务 sbin/hadoop-daemons.sh start journalnode //加个s就可以3台一块启动；都启动之后才能格式化namenode；只能格式化一次！2. 在[nn1]上，对其进行格式化，并启动 bin/hdfs namenode -format 19/02/13 02:15:00 INFO util.GSet: Computing capacity for map NameNodeRetryCache19/02/13 02:15:00 INFO util.GSet: VM type = 64-bit19/02/13 02:15:00 INFO util.GSet: 0.029999999329447746% max memory 889 MB = 273.1 KB19/02/13 02:15:00 INFO util.GSet: capacity = 2^15 = 32768 entries19/02/13 02:15:01 INFO namenode.FSImage: Allocated new BlockPoolId: BP-26035536-192.168.1.101-154999530180019/02/13 02:15:01 INFO common.Storage: Storage directory /opt/module/ha/hadoop-2.7.2/data/tmp/dfs/name has been successfully formatted.19/02/13 02:15:02 INFO namenode.NNStorageRetentionManager: Going to retain 1 images with txid >= 019/02/13 02:15:02 INFO util.ExitUtil: Exiting with status 019/02/13 02:15:02 INFO namenode.NameNode: SHUTDOWN_MSG: /************************************************************SHUTDOWN_MSG: Shutting down NameNode at hadoop101/192.168.1.101************************************************************/ 启动namenode: sbin/hadoop-daemon.sh start namenode3. 在[nn2]上，同步nn1的元数据信息 bin/hdfs namenode -bootstrapStandby......STARTUP_MSG: build = Unknown -r Unknown; compiled by 'root' on 2017-05-22T10:49ZSTARTUP_MSG: java = 1.8.0_144************************************************************/19/02/21 17:56:25 INFO namenode.NameNode: registered UNIX signal handlers for [TERM, HUP, INT]19/02/21 17:56:25 INFO namenode.NameNode: createNameNode [-bootstrapStandby]=====================================================About to bootstrap Standby ID nn2 from:Nameservice ID: myclusterOther Namenode ID: nn1Other NN's HTTP address: http://hadoop101:50070Other NN's IPC address: hadoop101/192.168.1.101:9000Namespace ID: 411281390Block pool ID: BP-1462258257-192.168.1.101-1550740170734Cluster ID: CID-d20dda0d-49d1-48f4-b9e8-2c99b72a15c2Layout version: -63isUpgradeFinalized: true=====================================================19/02/13 02:16:51 INFO common.Storage: Storage directory /opt/module/ha/hadoop-2.7.2/data/tmp/dfs/name has been successfully formatted.19/02/13 02:16:51 INFO namenode.TransferFsImage: Opening connection to http://hadoop101:50070/imagetransfer?getimage=1&txid=0&storageInfo=-63:1640720426:0:CID-81cbaa0d-6a6f-4932-98ba-ff2a46d8751419/02/13 02:16:51 INFO namenode.TransferFsImage: Image Transfer timeout configured to 60000 milliseconds19/02/13 02:16:52 INFO namenode.TransferFsImage: Transfer took 0.02s at 0.00 KB/s19/02/13 02:16:52 INFO namenode.TransferFsImage: Downloaded file fsimage.ckpt_0000000000000000000 size 351 bytes.19/02/13 02:16:52 INFO util.ExitUtil: Exiting with status 019/02/13 02:16:52 INFO namenode.NameNode: SHUTDOWN_MSG: /************************************************************SHUTDOWN_MSG: Shutting down NameNode at hadoop102/192.168.1.102************************************************************/出现这个信息是：（只需格式化一次；） Re-format filesystem in Storage Directory /opt/module/ha/hadoop-2.7.2/data/tmp/dfs/name ? (Y or N) N Format aborted in Storage Directory /opt/module/ha/hadoop-2.7.2/data/tmp/dfs/name 19/02/21 19:06:50 INFO util.ExitUtil: Exiting with status 5 ##这个是退出状态！ 19/02/21 19:06:50 INFO namenode.NameNode: SHUTDOWN_MSG: /************************************************************ SHUTDOWN_MSG: Shutting down NameNode at hadoop102/192.168.1.102 ************************************************************/
4. 启动[nn2] sbin/hadoop-daemon.sh start namenode6. 在[nn1]上，启动所有datanode； hadoop-daemons.sh是3台都启动datanode sbin/hadoop-daemons.sh start datanode ################手动切换namenode 7. 将[nn1]切换为Active bin/hdfs haadmin -transitionToActive nn15. 查看是否Active bin/hdfs haadmin -getServiceState nn1 http://hadoop101:50070/dfshealth.html#tab-overview http://hadoop102:50070/dfshealth.html#tab-overview
配置HDFS-HA自动故障转移（直接启动不需先按手动的启动方式）
配置好自动故障转移后手动模式就不可用了
Automatic failover is enabled for NameNode at hadoop102/192.168.1.102:9000Refusing to manually manage HA state, since it may cause a split-brain scenario or other incorrect state.If you are very sure you know what you are doing, please specify the --forcemanual flag.
配置HDFS-HA自动故障转移1. 具体配置 ；在上个基础上添加如下： （1）在hdfs-site.xml中增加（2）在core-site.xml文件中增加 dfs.ha.automatic-failover.enabled true 2. 启动 （1）关闭所有HDFS服务：sbin/stop-dfs.sh （2）启动Zookeeper集群：bin/zkServer.sh start （3）初始化HA在Zookeeper中状态：(只初始化一次)bin/hdfs zkfc -formatZK19/02/13 02:04:02 INFO zookeeper.ClientCnxn: Socket connection established to hadoop102/192.168.1.102:2181, initiating session19/02/13 02:04:02 INFO zookeeper.ClientCnxn: Session establishment complete on server hadoop102/192.168.1.102:2181, sessionid = 0x268e2dee6e40000, negotiated timeout = 500019/02/13 02:04:02 INFO ha.ActiveStandbyElector: Session connected.19/02/13 02:04:02 INFO ha.ActiveStandbyElector: Successfully created /hadoop-ha/mycluster in ZK.19/02/13 02:04:02 INFO zookeeper.ZooKeeper: Session: 0x268e2dee6e40000 closed19/02/13 02:04:02 INFO zookeeper.ClientCnxn: EventThread shut down （4）启动HDFS服务：sbin/start-dfs.shhadoop101: starting namenode, logging to /opt/module/ha/hadoop-2.7.2/logs/hadoop-kris-namenode-hadoop101.outhadoop102: starting namenode, logging to /opt/module/ha/hadoop-2.7.2/logs/hadoop-kris-namenode-hadoop102.outhadoop102: starting datanode, logging to /opt/module/ha/hadoop-2.7.2/logs/hadoop-kris-datanode-hadoop102.outhadoop101: starting datanode, logging to /opt/module/ha/hadoop-2.7.2/logs/hadoop-kris-datanode-hadoop101.outhadoop103: starting datanode, logging to /opt/module/ha/hadoop-2.7.2/logs/hadoop-kris-datanode-hadoop103.outStarting journal nodes [hadoop101 hadoop102 hadoop103]hadoop103: starting journalnode, logging to /opt/module/ha/hadoop-2.7.2/logs/hadoop-kris-journalnode-hadoop103.outhadoop102: starting journalnode, logging to /opt/module/ha/hadoop-2.7.2/logs/hadoop-kris-journalnode-hadoop102.outhadoop101: starting journalnode, logging to /opt/module/ha/hadoop-2.7.2/logs/hadoop-kris-journalnode-hadoop101.outStarting ZK Failover Controllers on NN hosts [hadoop101 hadoop102]hadoop101: starting zkfc, logging to /opt/module/ha/hadoop-2.7.2/logs/hadoop-kris-zkfc-hadoop101.outhadoop102: starting zkfc, logging to /opt/module/ha/hadoop-2.7.2/logs/hadoop-kris-zkfc-hadoop102.out3. 验证 （1）将Active NameNode进程kill kill -9 namenode的进程id ---> 另外一个namenode上位；( 杀掉之后，可单独启动: sbin/hadoop-daemon.sh start namenode，启动之后它不会变成之前的active；而是standby) (2) 将DFSZKFailoverController的进程kill kill -9 8819 --->尽管它的namenode没有挂，但另外一个namenode也会上位，它变成standby 再启动它要先停止->sbin/stop-dfs.sh sbin/start-dfs.sh （3）将Active NameNode机器断开网络 sudo service network stop ---> 把网络断开之后，配的隔离机制是sshfence尝试远程登录区杀敌hadoop101，直到把101网络连接上才杀死，102才成为active； ha.zookeeper.quorum hadoop101:2181,hadoop102:2181,hadoop103:2181
断网上位很容易脑裂，那边网已恢复就炸了；如果真的断网，它这个是不会自动切的是为了防脑裂。虽然可以通过配置断网可以直接上，但很危险；断网上不去反而安全。
[zk: localhost:2181(CONNECTED) 0] ls /[zookeeper, hadoop-ha][zk: localhost:2181(CONNECTED) 1] ls /[zookeeper, hadoop-ha][zk: localhost:2181(CONNECTED) 2] ls /hadoop-ha[mycluster][zk: localhost:2181(CONNECTED) 3] ls /hadoop-ha/mycluster[ActiveBreadCrumb, ActiveStandbyElectorLock] 选举的关键节点，谁占领了这个节点谁就是active； [zk: localhost:2181(CONNECTED) 4] get /hadoop-ha/mycluster/ActiveStandbyElectorLock myclusternn1 hadoop101 �F(�>cZxid = 0x10000000fctime = Wed Feb 13 02:16:22 CST 2019mZxid = 0x10000000fmtime = Wed Feb 13 02:16:22 CST 2019pZxid = 0x10000000fcversion = 0dataVersion = 0aclVersion = 0ephemeralOwner = 0x268e2dee6e40002 临时节点，dataLength = 33numChildren = 0
进程
hadoop101 hadoop102 hadoop103 NameNode NameNode JournalNode JournalNode JournalNode DataNode DataNode DataNode DFSZKFailoverController DFSZKFailoverController ZooKeeperMain（bin/zkCli.sh ,启动zookeeperd客户端） ResourceManager ResourceManager NodeManager NodeManager NodeManager QuorumPeerMain QuorumPeerMain QuorumPeerMain (bin/zkServer.sh start 启动zookeeper服务器)DFSZKFailoverController是Hadoop-2.7.0中HDFS NameNode HA实现的中心组件，它负责整体的故障转移控制等。它是一个守护进程，通过main()方法启动，继承自ZKFailoverController。 zkfc 使用JournalNode实现两个NameNode(Active和Standby)之间数据的共享
YARN-HA配置
YARN-HA工作机制
Yarn原生根zookeeper兼容很好，配置比较简单；
配置YARN-HA集群
yarn-site.xml
yarn.nodemanager.aux-services mapreduce_shuffle //混合服务还是shuffle，用shuffle确定reducer获取数据的方式yarn.resourcemanager.ha.enabled true yarn.resourcemanager.cluster-id cluster-yarn1 yarn.resourcemanager.ha.rm-ids rm1,rm2 yarn.resourcemanager.hostname.rm1 hadoop101 yarn.resourcemanager.hostname.rm2 hadoop102 yarn.resourcemanager.zk-address hadoop101:2181,hadoop102:2181,hadoop103:2181 yarn.resourcemanager.recovery.enabled true yarn.resourcemanager.store.class org.apache.hadoop.yarn.server.resourcemanager.recovery.ZKRMStateStore
yarn-site.xml 在hadoop101中配置好将其分发到其他机器：xsync etc/
启动zookeeper；3台其他都启动； [kris@hadoop101 ~]$ /opt/module/zookeeper-3.4.10/bin/zkServer.sh start启动hdfs sbin/start-dfs.sh启动YARN （1）在hadoop101中执行： sbin/start-yarn.sh[kris@hadoop101 hadoop-2.7.2]$ sbin/start-yarn.sh starting yarn daemonsstarting resourcemanager, logging to /opt/module/ha/hadoop-2.7.2/logs/yarn-kris-resourcemanager-hadoop101.outhadoop101: starting nodemanager, logging to /opt/module/ha/hadoop-2.7.2/logs/yarn-kris-nodemanager-hadoop101.outhadoop103: starting nodemanager, logging to /opt/module/ha/hadoop-2.7.2/logs/yarn-kris-nodemanager-hadoop103.outhadoop102: starting nodemanager, logging to /opt/module/ha/hadoop-2.7.2/logs/yarn-kris-nodemanager-hadoop102.out（2）在hadoop102中执行： sbin/yarn-daemon.sh start resourcemanager //脚本只在上面一台上启动了，hadoop102上的resourcemanager要手动启；[kris@hadoop102 hadoop-2.7.2]$ sbin/yarn-daemon.sh start resourcemanagerstarting resourcemanager, logging to /opt/module/ha/hadoop-2.7.2/logs/yarn-kris-resourcemanager-hadoop102.out（3）查看服务状态 bin/yarn rmadmin -getServiceState rm1 //rm1就是hadoop101; rm2为hadoop102[kris@hadoop102 hadoop-2.7.2]$ bin/yarn rmadmin -getServiceState rm1active[kris@hadoop102 hadoop-2.7.2]$ bin/yarn rmadmin -getServiceState rm2standby################hdfs-ha & yarn-ha[kris@hadoop101 hadoop-2.7.2]$ jpsall-------hadoop101-------14288 ResourceManager14402 NodeManager13396 NameNode14791 Jps13114 QuorumPeerMain13946 DFSZKFailoverController13516 DataNode13743 JournalNode-------hadoop102-------9936 NameNode10352 ResourceManager9569 JournalNode9698 DFSZKFailoverController9462 DataNode9270 QuorumPeerMain10600 Jps10202 NodeManager-------hadoop103-------9073 Jps8697 JournalNode8522 QuorumPeerMain8909 NodeManager8590 DataNode
http://hadoop101:8088/cluster http://hadoop102:8088/cluster -->它会重定向到hadoop101