1、首先namenode无法启动，第一时间查看日志，看看具体是什么原因。
2、namenode无法启动，主要还是配置文件的错误，其次就是用户权限的问题。
3、日志错误如下：
2018-06-02 23:57:20,316 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: STARTUP_MSG:
/************************************************************STARTUP_MSG: Starting NameNode
STARTUP_MSG: host = hadoop/127.0.1.1
STARTUP_MSG: args = []
STARTUP_MSG: version = 2.6.4
STARTUP_MSG: classpath = /usr/local/hadoop/etc/hadoop:/usr/local/hadoop/share/hadoop/common/lib/jaxb-api-2.2.2.jar:/usr/local/hadoop/share/hadoop/common/lib/jasper-runtime-5.5.23.jar:/usr/local/hadoop/share/hadoop/common/lib/hamcrest-core-1.3.jar:/usr/local/hadoop/share/hadoop/common/lib/xz-1.0.jar:/usr/local/hadoop/share/hadoop/common/lib/jetty-6.1.26.jar:/usr/local/hadoop/share/hadoop/common/lib/gson-2.2.4.jar:/usr/local/hadoop/share/hadoop/common/lib/hadoop-annotations-2.6.4.jar:/usr/local/hadoop/share/hadoop/common/lib/commons-el-1.0.jar:/usr/local/hadoop/share/hadoop/common/lib/commons-collections-3.2.2.jar:/usr/local/hadoop/share/hadoop/common/lib/jsp-api-2.1.jar:/usr/local/hadoop/share/hadoop/common/lib/jersey-json-1.9.jar:/usr/local/hadoop/share/hadoop/common/lib/commons-codec-1.4.jar:/usr/local/hadoop/share/hadoop/common/lib/commons-beanutils-1.7.0.jar:/usr/local/hadoop/share/hadoop/common/lib/paranamer-2.3.jar:/usr/local/hadoop/share/hadoop/common/lib/jets3t-0.9.0.jar:/usr/local/hadoop/share/hadoop/common/lib/commons-compress-1.4.1.jar:/usr/local/hadoop/share/hadoop/common/lib/apacheds-i18n-2.0.0-M15.jar:/usr/local/hadoop/share/hadoop/common/lib/commons-digester-1.8.jar:/usr/local/hadoop/share/hadoop/common/lib/java-xmlbuilder-0.4.jar:/usr/local/hadoop/share/hadoop/common/lib/jsch-0.1.42.jar:/usr/local/hadoop/share/hadoop/common/lib/mockito-all-1.8.5.jar:/usr/local/hadoop/share/hadoop/common/lib/activation-1.1.jar:/usr/local/hadoop/share/hadoop/common/lib/jersey-server-1.9.jar:/usr/local/hadoop/share/hadoop/common/lib/commons-cli-1.2.jar:/usr/local/hadoop/share/hadoop/common/lib/curator-framework-2.6.0.jar:/usr/local/hadoop/share/hadoop/common/lib/asm-3.2.jar:/usr/local/hadoop/share/hadoop/common/lib/commons-math3-3.1.1.jar:/usr/local/hadoop/share/hadoop/common/lib/jetty-util-6.1.26.jar:/usr/local/hadoop/share/hadoop/common/lib/protobuf-java-2.5.0.jar:/usr/local/hadoop/share/hadoop/common/lib/curator-recipes-2.6.0.jar:/usr/local/hadoop/share/hadoop/common/lib/slf4j-log4j12-1.7.5.jar:/usr/local/hadoop/share/hadoop/common/lib/avro-1.7.4.jar:/usr/local/hadoop/share/hadoop/common/lib/hadoop-auth-2.6.4.jar:/usr/local/hadoop/share/hadoop/common/lib/snappy-java-1.0.4.1.jar:/usr/local/hadoop/share/hadoop/common/lib/httpcore-4.2.5.jar:/usr/local/hadoop/share/hadoop/common/lib/apacheds-kerberos-codec-2.0.0-M15.jar:/usr/local/hadoop/share/hadoop/common/lib/commons-configuration-1.6.jar:/usr/local/hadoop/share/hadoop/common/lib/servlet-api-2.5.jar:/usr/local/hadoop/share/hadoop/common/lib/commons-net-3.1.jar:/usr/local/hadoop/share/hadoop/common/lib/api-asn1-api-1.0.0-M20.jar:/usr/local/hadoop/share/hadoop/common/lib/jackson-xc-1.9.13.jar:/usr/local/hadoop/share/hadoop/common/lib/log4j-1.2.17.jar:/usr/local/hadoop/share/hadoop/common/lib/stax-api-1.0-2.jar:/usr/local/hadoop/share/hadoop/common/lib/guava-11.0.2.jar:/usr/local/hadoop/share/hadoop/common/lib/jackson-jaxrs-1.9.13.jar:/usr/local/hadoop/share/hadoop/common/lib/httpclient-4.2.5.jar:/usr/local/hadoop/share/hadoop/common/lib/jackson-mapper-asl-1.9.13.jar:/usr/local/hadoop/share/hadoop/common/lib/jasper-compiler-5.5.23.jar:/usr/local/hadoop/share/hadoop/common/lib/commons-logging-1.1.3.jar:/usr/local/hadoop/share/hadoop/common/lib/jsr305-1.3.9.jar:/usr/local/hadoop/share/hadoop/common/lib/jackson-core-asl-1.9.13.jar:/usr/local/hadoop/share/hadoop/common/lib/jersey-core-1.9.jar:/usr/local/hadoop/share/hadoop/common/lib/commons-io-2.4.jar:/usr/local/hadoop/share/hadoop/common/lib/commons-beanutils-core-1.8.0.jar:/usr/local/hadoop/share/hadoop/common/lib/commons-httpclient-3.1.jar:/usr/local/hadoop/share/hadoop/common/lib/jettison-1.1.jar:/usr/local/hadoop/share/hadoop/common/lib/zookeeper-3.4.6.jar:/usr/local/hadoop/share/hadoop/common/lib/jaxb-impl-2.2.3-1.jar:/usr/local/hadoop/share/hadoop/common/lib/commons-lang-2.6.jar:/usr/local/hadoop/share/hadoop/common/lib/netty-3.6.2.Final.jar:/usr/local/hadoop/share/hadoop/common/lib/curator-client-2.6.0.jar:/usr/local/hadoop/share/hadoop/common/lib/htrace-core-3.0.4.jar:/usr/local/hadoop/share/hadoop/common/lib/api-util-1.0.0-M20.jar:/usr/local/hadoop/share/hadoop/common/lib/xmlenc-0.52.jar:/usr/local/hadoop/share/hadoop/common/lib/junit-4.11.jar:/usr/local/hadoop/share/hadoop/common/lib/slf4j-api-1.7.5.jar:/usr/local/hadoop/share/hadoop/common/hadoop-common-2.6.4-tests.jar:/usr/local/hadoop/share/hadoop/common/hadoop-nfs-2.6.4.jar:/usr/local/hadoop/share/hadoop/common/hadoop-common-2.6.4.jar:/usr/local/hadoop/share/hadoop/hdfs:/usr/local/hadoop/share/hadoop/hdfs/lib/commons-daemon-1.0.13.jar:/usr/local/hadoop/share/hadoop/hdfs/lib/jasper-runtime-5.5.23.jar:/usr/local/hadoop/share/hadoop/hdfs/lib/xml-apis-1.3.04.jar:/usr/local/hadoop/share/hadoop/hdfs/lib/jetty-6.1.26.jar:/usr/local/hadoop/share/hadoop/hdfs/lib/commons-el-1.0.jar:/usr/local/hadoop/share/hadoop/hdfs/lib/jsp-api-2.1.jar:/usr/local/hadoop/share/hadoop/hdfs/lib/commons-codec-1.4.jar:/usr/local/hadoop/share/hadoop/hdfs/lib/jersey-server-1.9.jar:/usr/local/hadoop/share/hadoop/hdfs/lib/commons-cli-1.2.jar:/usr/local/hadoop/share/hadoop/hdfs/lib/asm-3.2.jar:/usr/local/hadoop/share/hadoop/hdfs/lib/jetty-util-6.1.26.jar:/usr/local/hadoop/share/hadoop/hdfs/lib/protobuf-java-2.5.0.jar:/usr/local/hadoop/share/hadoop/hdfs/lib/servlet-api-2.5.jar:/usr/local/hadoop/share/hadoop/hdfs/lib/xercesImpl-2.9.1.jar:/usr/local/hadoop/share/hadoop/hdfs/lib/log4j-1.2.17.jar:/usr/local/hadoop/share/hadoop/hdfs/lib/guava-11.0.2.jar:/usr/local/hadoop/share/hadoop/hdfs/lib/jackson-mapper-asl-1.9.13.jar:/usr/local/hadoop/share/hadoop/hdfs/lib/commons-logging-1.1.3.jar:/usr/local/hadoop/share/hadoop/hdfs/lib/jsr305-1.3.9.jar:/usr/local/hadoop/share/hadoop/hdfs/lib/jackson-core-asl-1.9.13.jar:/usr/local/hadoop/share/hadoop/hdfs/lib/jersey-core-1.9.jar:/usr/local/hadoop/share/hadoop/hdfs/lib/commons-io-2.4.jar:/usr/local/hadoop/share/hadoop/hdfs/lib/commons-lang-2.6.jar:/usr/local/hadoop/share/hadoop/hdfs/lib/netty-3.6.2.Final.jar:/usr/local/hadoop/share/hadoop/hdfs/lib/htrace-core-3.0.4.jar:/usr/local/hadoop/share/hadoop/hdfs/lib/xmlenc-0.52.jar:/usr/local/hadoop/share/hadoop/hdfs/hadoop-hdfs-2.6.4-tests.jar:/usr/local/hadoop/share/hadoop/hdfs/hadoop-hdfs-2.6.4.jar:/usr/local/hadoop/share/hadoop/hdfs/hadoop-hdfs-nfs-2.6.4.jar:/usr/local/hadoop/share/hadoop/yarn/lib/jaxb-api-2.2.2.jar:/usr/local/hadoop/share/hadoop/yarn/lib/guice-3.0.jar:/usr/local/hadoop/share/hadoop/yarn/lib/xz-1.0.jar:/usr/local/hadoop/share/hadoop/yarn/lib/jetty-6.1.26.jar:/usr/local/hadoop/share/hadoop/yarn/lib/commons-collections-3.2.2.jar:/usr/local/hadoop/share/hadoop/yarn/lib/jersey-json-1.9.jar:/usr/local/hadoop/share/hadoop/yarn/lib/commons-codec-1.4.jar:/usr/local/hadoop/share/hadoop/yarn/lib/jline-0.9.94.jar:/usr/local/hadoop/share/hadoop/yarn/lib/commons-compress-1.4.1.jar:/usr/local/hadoop/share/hadoop/yarn/lib/activation-1.1.jar:/usr/local/hadoop/share/hadoop/yarn/lib/leveldbjni-all-1.8.jar:/usr/local/hadoop/share/hadoop/yarn/lib/jersey-server-1.9.jar:/usr/local/hadoop/share/hadoop/yarn/lib/commons-cli-1.2.jar:/usr/local/hadoop/share/hadoop/yarn/lib/asm-3.2.jar:/usr/local/hadoop/share/hadoop/yarn/lib/jetty-util-6.1.26.jar:/usr/local/hadoop/share/hadoop/yarn/lib/protobuf-java-2.5.0.jar:/usr/local/hadoop/share/hadoop/yarn/lib/jersey-guice-1.9.jar:/usr/local/hadoop/share/hadoop/yarn/lib/javax.inject-1.jar:/usr/local/hadoop/share/hadoop/yarn/lib/servlet-api-2.5.jar:/usr/local/hadoop/share/hadoop/yarn/lib/jackson-xc-1.9.13.jar:/usr/local/hadoop/share/hadoop/yarn/lib/log4j-1.2.17.jar:/usr/local/hadoop/share/hadoop/yarn/lib/stax-api-1.0-2.jar:/usr/local/hadoop/share/hadoop/yarn/lib/guava-11.0.2.jar:/usr/local/hadoop/share/hadoop/yarn/lib/jackson-jaxrs-1.9.13.jar:/usr/local/hadoop/share/hadoop/yarn/lib/aopalliance-1.0.jar:/usr/local/hadoop/share/hadoop/yarn/lib/jackson-mapper-asl-1.9.13.jar:/usr/local/hadoop/share/hadoop/yarn/lib/commons-logging-1.1.3.jar:/usr/local/hadoop/share/hadoop/yarn/lib/jsr305-1.3.9.jar:/usr/local/hadoop/share/hadoop/yarn/lib/jackson-core-asl-1.9.13.jar:/usr/local/hadoop/share/hadoop/yarn/lib/guice-servlet-3.0.jar:/usr/local/hadoop/share/hadoop/yarn/lib/jersey-core-1.9.jar:/usr/local/hadoop/share/hadoop/yarn/lib/commons-io-2.4.jar:/usr/local/hadoop/share/hadoop/yarn/lib/jersey-client-1.9.jar:/usr/local/hadoop/share/hadoop/yarn/lib/commons-httpclient-3.1.jar:/usr/local/hadoop/share/hadoop/yarn/lib/jettison-1.1.jar:/usr/local/hadoop/share/hadoop/yarn/lib/zookeeper-3.4.6.jar:/usr/local/hadoop/share/hadoop/yarn/lib/jaxb-impl-2.2.3-1.jar:/usr/local/hadoop/share/hadoop/yarn/lib/commons-lang-2.6.jar:/usr/local/hadoop/share/hadoop/yarn/lib/netty-3.6.2.Final.jar:/usr/local/hadoop/share/hadoop/yarn/hadoop-yarn-applications-distributedshell-2.6.4.jar:/usr/local/hadoop/share/hadoop/yarn/hadoop-yarn-server-nodemanager-2.6.4.jar:/usr/local/hadoop/share/hadoop/yarn/hadoop-yarn-server-tests-2.6.4.jar:/usr/local/hadoop/share/hadoop/yarn/hadoop-yarn-client-2.6.4.jar:/usr/local/hadoop/share/hadoop/yarn/hadoop-yarn-server-resourcemanager-2.6.4.jar:/usr/local/hadoop/share/hadoop/yarn/hadoop-yarn-server-common-2.6.4.jar:/usr/local/hadoop/share/hadoop/yarn/hadoop-yarn-common-2.6.4.jar:/usr/local/hadoop/share/hadoop/yarn/hadoop-yarn-applications-unmanaged-am-launcher-2.6.4.jar:/usr/local/hadoop/share/hadoop/yarn/hadoop-yarn-api-2.6.4.jar:/usr/local/hadoop/share/hadoop/yarn/hadoop-yarn-server-web-proxy-2.6.4.jar:/usr/local/hadoop/share/hadoop/yarn/hadoop-yarn-registry-2.6.4.jar:/usr/local/hadoop/share/hadoop/yarn/hadoop-yarn-server-applicationhistoryservice-2.6.4.jar:/usr/local/hadoop/share/hadoop/mapreduce/lib/guice-3.0.jar:/usr/local/hadoop/share/hadoop/mapreduce/lib/hamcrest-core-1.3.jar:/usr/local/hadoop/share/hadoop/mapreduce/lib/xz-1.0.jar:/usr/local/hadoop/share/hadoop/mapreduce/lib/hadoop-annotations-2.6.4.jar:/usr/local/hadoop/share/hadoop/mapreduce/lib/paranamer-2.3.jar:/usr/local/hadoop/share/hadoop/mapreduce/lib/commons-compress-1.4.1.jar:/usr/local/hadoop/share/hadoop/mapreduce/lib/leveldbjni-all-1.8.jar:/usr/local/hadoop/share/hadoop/mapreduce/lib/jersey-server-1.9.jar:/usr/local/hadoop/share/hadoop/mapreduce/lib/asm-3.2.jar:/usr/local/hadoop/share/hadoop/mapreduce/lib/protobuf-java-2.5.0.jar:/usr/local/hadoop/share/hadoop/mapreduce/lib/jersey-guice-1.9.jar:/usr/local/hadoop/share/hadoop/mapreduce/lib/avro-1.7.4.jar:/usr/local/hadoop/share/hadoop/mapreduce/lib/snappy-java-1.0.4.1.jar:/usr/local/hadoop/share/hadoop/mapreduce/lib/javax.inject-1.jar:/usr/local/hadoop/share/hadoop/mapreduce/lib/log4j-1.2.17.jar:/usr/local/hadoop/share/hadoop/mapreduce/lib/aopalliance-1.0.jar:/usr/local/hadoop/share/hadoop/mapreduce/lib/jackson-mapper-asl-1.9.13.jar:/usr/local/hadoop/share/hadoop/mapreduce/lib/jackson-core-asl-1.9.13.jar:/usr/local/hadoop/share/hadoop/mapreduce/lib/guice-servlet-3.0.jar:/usr/local/hadoop/share/hadoop/mapreduce/lib/jersey-core-1.9.jar:/usr/local/hadoop/share/hadoop/mapreduce/lib/commons-io-2.4.jar:/usr/local/hadoop/share/hadoop/mapreduce/lib/netty-3.6.2.Final.jar:/usr/local/hadoop/share/hadoop/mapreduce/lib/junit-4.11.jar:/usr/local/hadoop/share/hadoop/mapreduce/hadoop-mapreduce-examples-2.6.4.jar:/usr/local/hadoop/share/hadoop/mapreduce/hadoop-mapreduce-client-hs-plugins-2.6.4.jar:/usr/local/hadoop/share/hadoop/mapreduce/hadoop-mapreduce-client-common-2.6.4.jar:/usr/local/hadoop/share/hadoop/mapreduce/hadoop-mapreduce-client-jobclient-2.6.4-tests.jar:/usr/local/hadoop/share/hadoop/mapreduce/hadoop-mapreduce-client-jobclient-2.6.4.jar:/usr/local/hadoop/share/hadoop/mapreduce/hadoop-mapreduce-client-app-2.6.4.jar:/usr/local/hadoop/share/hadoop/mapreduce/hadoop-mapreduce-client-hs-2.6.4.jar:/usr/local/hadoop/share/hadoop/mapreduce/hadoop-mapreduce-client-core-2.6.4.jar:/usr/local/hadoop/share/hadoop/mapreduce/hadoop-mapreduce-client-shuffle-2.6.4.jar:/contrib/capacity-scheduler/*.jar:/contrib/capacity-scheduler/*.jar:/contrib/capacity-scheduler/*.jar
STARTUP_MSG: build = https://git-wip-us.apache.org/repos/asf/hadoop.git -r 5082c73637530b0b7e115f9625ed7fac69f937e6; compiled by 'jenkins' on 2016-02-12T09:45Z
STARTUP_MSG: java = 1.8.0_171
************************************************************/
2018-06-02 23:57:20,330 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: registered UNIX signal handlers for [TERM, HUP, INT]
2018-06-02 23:57:20,335 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: createNameNode []
2018-06-02 23:57:20,753 INFO org.apache.hadoop.metrics2.impl.MetricsConfig: loaded properties from hadoop-metrics2.properties
2018-06-02 23:57:20,932 INFO org.apache.hadoop.metrics2.impl.MetricsSystemImpl: Scheduled snapshot period at 10 second(s).
2018-06-02 23:57:20,932 INFO org.apache.hadoop.metrics2.impl.MetricsSystemImpl: NameNode metrics system started
2018-06-02 23:57:20,932 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: fs.defaultFS is hdfs://localhost:9000
2018-06-02 23:57:20,933 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: Clients are to use localhost:9000 to access this namenode/service.
2018-06-02 23:57:21,252 INFO org.apache.hadoop.hdfs.DFSUtil: Starting Web-server for hdfs at: http://0.0.0.0:50070
2018-06-02 23:57:21,314 INFO org.mortbay.log: Logging to org.slf4j.impl.Log4jLoggerAdapter(org.mortbay.log) via org.mortbay.log.Slf4jLog
2018-06-02 23:57:21,320 INFO org.apache.hadoop.http.HttpRequestLog: Http request log for http.requests.namenode is not defined
2018-06-02 23:57:21,332 INFO org.apache.hadoop.http.HttpServer2: Added global filter 'safety' (class=org.apache.hadoop.http.HttpServer2$QuotingInputFilter)
2018-06-02 23:57:21,338 INFO org.apache.hadoop.http.HttpServer2: Added filter static_user_filter (class=org.apache.hadoop.http.lib.StaticUserWebFilter$StaticUserFilter) to context hdfs
2018-06-02 23:57:21,338 INFO org.apache.hadoop.http.HttpServer2: Added filter static_user_filter (class=org.apache.hadoop.http.lib.StaticUserWebFilter$StaticUserFilter) to context logs
2018-06-02 23:57:21,338 INFO org.apache.hadoop.http.HttpServer2: Added filter static_user_filter (class=org.apache.hadoop.http.lib.StaticUserWebFilter$StaticUserFilter) to context static
2018-06-02 23:57:21,366 INFO org.apache.hadoop.http.HttpServer2: Added filter 'org.apache.hadoop.hdfs.web.AuthFilter' (class=org.apache.hadoop.hdfs.web.AuthFilter)
2018-06-02 23:57:21,367 INFO org.apache.hadoop.http.HttpServer2: addJerseyResourcePackage: packageName=org.apache.hadoop.hdfs.server.namenode.web.resources;org.apache.hadoop.hdfs.web.resources, pathSpec=/webhdfs/v1/*
2018-06-02 23:57:21,407 INFO org.apache.hadoop.http.HttpServer2: Jetty bound to port 50070
2018-06-02 23:57:21,407 INFO org.mortbay.log: jetty-6.1.26
2018-06-02 23:57:21,736 INFO org.mortbay.log: Started [email protected]:50070
2018-06-02 23:57:21,774 WARN org.apache.hadoop.hdfs.server.namenode.FSNamesystem: Only one image storage directory (dfs.namenode.name.dir) configured. Beware of data loss due to lack of redundant storage directories!
2018-06-02 23:57:21,774 WARN org.apache.hadoop.hdfs.server.namenode.FSNamesystem: Only one namespace edits storage directory (dfs.namenode.edits.dir) configured. Beware of data loss due to lack of redundant storage directories!
2018-06-02 23:57:21,781 FATAL org.apache.hadoop.hdfs.server.namenode.NameNode: Failed to start namenode.
java.lang.NullPointerException
at java.io.File.<init>(File.java:277)
at org.apache.hadoop.hdfs.server.namenode.NNStorage.setStorageDirectories(NNStorage.java:305)
at org.apache.hadoop.hdfs.server.namenode.NNStorage.<init>(NNStorage.java:166)
at org.apache.hadoop.hdfs.server.namenode.FSImage.<init>(FSImage.java:127)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.loadFromDisk(FSNamesystem.java:730)
at org.apache.hadoop.hdfs.server.namenode.NameNode.loadNamesystem(NameNode.java:538)
at org.apache.hadoop.hdfs.server.namenode.NameNode.initialize(NameNode.java:597)
at org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:764)
at org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:748)
at org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:1441)
at org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:1507)
2018-06-02 23:57:21,789 INFO org.apache.hadoop.util.ExitUtil: Exiting with status 1
2018-06-02 23:57:21,790 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: SHUTDOWN_MSG:
/************************************************************
SHUTDOWN_MSG: Shutting down NameNode at hadoop/127.0.1.1
************************************************************/
本人这次是因为hdfs-site.xml配置错误所致。
在hdfs-site.xml配置中，使用了file:标识符，可以直接使用/代替即可。
4、格式一般只能格式化一次，第二格式化时，需要删除hdfs-site.xml中hdfs的文件配置目录，然后再格式化才能生效。