【HDFS】HDFS與dfsadmin結合使用

1.獲取所有參數

[hadoop@node01 ~]$ hdfs dfsadmin
Usage: hdfs dfsadmin
Note: Administrative commands can only be run as the HDFS superuser.
        [-report [-live] [-dead] [-decommissioning]]
        [-safemode <enter | leave | get | wait>]
        [-saveNamespace]
        [-rollEdits]
        [-restoreFailedStorage true|false|check]
        [-refreshNodes]
        [-setQuota <quota> <dirname>...<dirname>]
        [-clrQuota <dirname>...<dirname>]
        [-setSpaceQuota <quota> <dirname>...<dirname>]
        [-clrSpaceQuota <dirname>...<dirname>]
        [-finalizeUpgrade]
        [-rollingUpgrade [<query|prepare|finalize>]]
        [-refreshServiceAcl]
        [-refreshUserToGroupsMappings]
        [-refreshSuperUserGroupsConfiguration]
        [-refreshCallQueue]
        [-refresh <host:ipc_port> <key> [arg1..argn]
        [-reconfig <datanode|...> <host:ipc_port> <start|status|properties>]
        [-printTopology]
        [-refreshNamenodes datanode_host:ipc_port]
        [-deleteBlockPool datanode_host:ipc_port blockpoolId [force]]
        [-setBalancerBandwidth <bandwidth in bytes per second>]
        [-fetchImage <local directory>]
        [-allowSnapshot <snapshotDir>]
        [-disallowSnapshot <snapshotDir>]
        [-shutdownDatanode <datanode_host:ipc_port> [upgrade]]
        [-getDatanodeInfo <datanode_host:ipc_port>]
        [-metasave filename]
        [-triggerBlockReport [-incremental] <datanode_host:ipc_port>]
        [-listOpenFiles]
        [-help [cmd]]

Generic options supported are
-conf <configuration file>     specify an application configuration file
-D <property=value>            use value for given property
-fs <local|namenode:port>      specify a namenode
-jt <local|resourcemanager:port>    specify a ResourceManager
-files <comma separated list of files>    specify comma separated files to be copied to the map reduce cluster
-libjars <comma separated list of jars>    specify comma separated jar files to include in the classpath.
-archives <comma separated list of archives>    specify comma separated archives to be unarchived on the compute machines.

The general command line syntax is
bin/hadoop command [genericOptions] [commandOptions]

2.查看當前模式

[hadoop@node01 ~]$ hdfs dfsadmin -safemode get
Safe mode is OFF

3.進入和離開安全模式

[hadoop@node01 ~]$ hdfs dfsadmin -safemode enter
Safe mode is ON
[hadoop@node01 ~]$ hdfs dfsadmin -safemode leave
Safe mode is OFF