《快学BigData》--Hadoop总结（E）（38）

Hadoop总结 - - - - - - - - - - - - - - - - - - - - - - - - - - - - 210

概述 - - - - - - - - - - - - - - - - - - - - - - - - - - - - 211

CDH - - - - - - - - - - - - - - - - - - - - - - - - - - - - 211

安装Hadoop2.6.4 非Zookeeper集群版 - - - - - - - - - - - - - - - 211

安装Hadoop2.6.4 Zookeeper集群版 - - - - - - - - - - - - - - - 216

MapReduce整体的流程详解 - - - - - - - - - - - - - - - - - - - - 225

Hadoop HDFS 系统详解 - - - - - - - - - - - - - - - - - - - - - 226

JAVA 操作HDFS - - - - - - - - - - - - - - - - - - - - - - - - 241

Hadoop MapReduce 实例 - - - - - - - - - - - - - - - - - - - - 248

Hadoop 其他总结 - - - - - - - - - - - - - - - - - - - - - - - - 259

Hadoop 优化总结 - - - - - - - - - - - - - - - - - - - - - - - - 259

HDFS误删除恢复方法

我们每天面对hdfs命令，有时会误删除文件，怎样才能把误删除的文件恢复呢，接下来详细的讲解一下过程

1-1）、通过垃圾箱恢复

A）、准备数据

# vi test.txt

# hadoop fs -put test.txt /user/root

# hadoop fs -ls /user/root

Found 1 items

-rw-r--r-- 3 root hdfs 12 2018-01-31 08:25 /user/root/test.txt

B）、对文件进行删除

# hadoop fs -rmr /user/root/test.txt

rmr: DEPRECATED: Please use 'rm -r' instead.

18/01/31 08:26:16 INFO fs.TrashPolicyDefault: Moved: 'hdfs://rdsp-cn-01.cars.com:8020/user/root/test.txt' to trash at: hdfs://rdsp-cn-01.cars.com:8020/user/root/.Trash/Current/user/root/test.txt

可以看出已经把文件放到垃圾箱了

C）、恢复删除的数据

# hadoop fs -ls /user/root/.Trash/Current/user/root/

Found 1 items

-rw-r--r-- 3 root hdfs 12 2018-01-31 08:25 /user/root/.Trash/Current/user/root/test.txt

# hadoop fs -mv /user/root/.Trash/Current/user/root/test.txt /user/root/

# hadoop fs -ls /user/root/root

Found 1 items

-rw-r--r-- 3 root hdfs 12 2018-01-31 08:25 /user/root/test.txt

D）、查看配置

次选项在conf下的core-site.xml中，单位是分钟，如果一天便是:60*24=1440

1-2）、通过快照恢复

A）、创建目录和文件

# hadoop fs -put test.txt /user/root

# hadoop fs -cat /user/root/root/test.txt

123

456

789

B）、创建快照

# hadoop dfsadmin -allowSnapshot /user/root/root

DEPRECATED: Use of this script to execute hdfs command is deprecated.

Instead use the hdfs command for it.

Allowing snaphot on /user/root/root succeeded

# hadoop fs -createSnapshot /user/root/root/ test-snapshot

Created snapshot /user/root/root/.snapshot/test-snapshot

可以看出来创建的快照是test-snapshot

C）、删除文件

# hadoop fs -rmr /user/root/root/test.txt

rmr: DEPRECATED: Please use 'rm -r' instead.

18/01/31 09:02:55 INFO fs.TrashPolicyDefault: Moved: 'hdfs://rdsp-cn-01.cars.com:8020/user/root/root/test.txt' to trash at: hdfs://rdsp-cn-01.cars.com:8020/user/root/.Trash/Current/user/root/root/test.txt

D）、恢复文件

# hadoop fs -ls /user/root/root/.snapshot/test-snapshot

Found 1 items

-rw-r--r-- 3 root hdfs 12 2018-01-31 08:25 /user/root/root/.snapshot/test-snapshot/test.txt

# hadoop fs -cp /user/root/root/.snapshot/test-snapshot/test.txt /user/root/root/

# hadoop fs -ls /user/root/root/

Found 1 items

-rw-r--r-- 3 root hdfs 12 2018-01-31 09:06 /user/root/root/test.txt