HDFS快照
- 在data目录下启用快照
[xiaoqiu@s150 /home/xiaoqiu/hadoop_tmp]$ hdfs dfsadmin -allowSnapshot data
- 创建快照
[xiaoqiu@s150 /home/xiaoqiu/hadoop_tmp]$ hdfs dfs -createSnapshot data ss1
- 查看快照信息
[xiaoqiu@s150 /home/xiaoqiu]$ hdfs dfs -lsr /user/xiaoqiu/data/.snapshot/ss1
lsr: DEPRECATED: Please use 'ls -R' instead.
-rw-r--r-- 2 xiaoqiu supergroup 4 2017-12-29 16:08 /user/xiaoqiu/data/.snapshot/ss1/1.txt
drwxr-xr-x - xiaoqiu supergroup 0 2017-12-29 15:57 /user/xiaoqiu/data/.snapshot/ss1/a
drwxr-xr-x - xiaoqiu supergroup 0 2017-12-29 15:57 /user/xiaoqiu/data/.snapshot/ss1/a/b
[xiaoqiu@s150 /home/xiaoqiu]$
- web访问快照信息
- 快照并不会产生新的文件,我们可以通过查看ID
- 对HDFS的文件进行修改
[xiaoqiu@s150 /home/xiaoqiu]$ echo aaa > 2.txt
[xiaoqiu@s150 /home/xiaoqiu]$ hdfs dfs -appendToFile 2.txt data/1.txt
[xiaoqiu@s150 /home/xiaoqiu]$ hdfs dfs -cat data/1.txt
123
aaa
[xiaoqiu@s150 /home/xiaoqiu]$ hdfs dfs -cat data/.snapshot/ss1
cat: `data/.snapshot/ss1': Is a directory
[xiaoqiu@s150 /home/xiaoqiu]$ hdfs dfs -cat data/.snapshot/ss1/1.txt
123
[xiaoqiu@s150 /home/xiaoqiu]$
- 删除快照
[xiaoqiu@s150 /home/xiaoqiu]$ hdfs dfs -deleteSnapshot data ss1
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