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
