已解决：Hadoop启动HDFS时，丢失Namenode/Datanode。_hadoop namenode -format warning: use of this scrip-优快云博客

已解决：Hadoop启动HDFS时，丢失namenode进程。

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There appears to be a gap in the edit log.  We expected txid 1, but got txid 102.

[root@chensy logs]# hadoop namenode -recover #也许是namenode数据元丢失
DEPRECATED: Use of this script to execute hdfs command is deprecated.
Instead use the hdfs command for it.

21/03/25 09:37:32 INFO namenode.NameNode: STARTUP_MSG: 
/************************************************************
STARTUP_MSG: Starting NameNode

...
Are you ready to proceed? (Y/N)
 (Y or N) y
...
Enter 'a' to always select the first choice in the future without prompting. (c/s/q/a)
c

[root@chensy logs]# jps #查看进程，namenode已经正常开启，但是我们发现却失去了Datanode
10034 SecondaryNameNode
10149 Jps
9720 NameNode

查看报错日志

[root@chensy hadoop-2.7.3]# cd logs
[root@chensy logs]# pwd
/data/module/hadoop-2.7.3/logs
[root@chensy logs]# ll
总用量 2368
-rw-r--r--. 1 root root 638095 3月  25 10:57 hadoop-root-datanode-chensy.log

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进到/data/module/hadoop-2.7.3/tmp/dfs/name/current
目录下

[root@chensy current]# vi VERSION
#按照下面的改

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[root@chensy current]# start-dfs.sh
Starting namenodes on [chensy]
chensy: starting namenode, logging to /data/module/hadoop-2.7.3/logs/hadoop-root-namenode-chensy.out
localhost: starting datanode, logging to /data/module/hadoop-2.7.3/logs/hadoop-root-datanode-chensy.out
Starting secondary namenodes [0.0.0.0]
0.0.0.0: starting secondarynamenode, logging to /data/module/hadoop-2.7.3/logs/hadoop-root-secondarynamenode-chensy.out
[root@chensy current]# jps #就出现了datanode
12449 DataNode
12626 SecondaryNameNode
12308 NameNode
12741 Jps