hadoop启动namenode日志报这个错，首先说怎么看日志

hadoop启动namenode日志报这个错，首先说怎么看日志，

启动namenode会有这个，ubuntu: starting namenode, logging to /home/xiaoye/hadoop/logs/hadoop-xiaoye-namenode-ubuntu.out

这是hadoop启动时会自动帮助写日志，并告诉我们日志的目录，我直接tail -200 /home/xiaoye/hadoop/logs/hadoop-xiaoye-namenode-ubuntu.out 看日志后200行，可是出现的结果是：

xiaoye@ubuntu:~$ tail -200 hadoop/logs/hadoop-xiaoye-namenode-ubuntu.out

ulimit -a for user xiaoye

core file size          (blocks, -c) 0

data seg size           (kbytes, -d) unlimited

scheduling priority             (-e) 0

file size               (blocks, -f) unlimited

pending signals                 (-i) 3645

max locked memory       (kbytes, -l) 64

max memory size         (kbytes, -m) unlimited

open files                      (-n) 1024

pipe size            (512 bytes, -p) 8

POSIX message queues     (bytes, -q) 819200

real-time priority              (-r) 0

stack size              (kbytes, -s) 8192

cpu time               (seconds, -t) unlimited

max user processes              (-u) 3645

virtual memory          (kbytes, -v) unlimited

file locks                      (-x) unlimited

应该不是这个日志啊，看着不对劲。

于是改成   tail -200 hadoop/logs/hadoop-xiaoye-namenode-ubuntu.log

这个命令，就可以看到出现这个错，NameNode has nsId 229502726 but storage has nsId 695608861

解决办法：原因分析：

是多次格式化namenode导致版本不一致，直接的办法是直接删掉hadoop/hadoop/目录下的data和name目录下的所有文件，然后重新格式化，重新启动。但是这样明显是不提倡的。

这里解决办法是改文件的内容，根据提示，把/hadoop/hadoop/name/current目录下的VERSION文件的namespaceID修改成报错信息中storage的id值。

xiaoye@ubuntu:~$ cd hadoop/hadoop/name/current

xiaoye@ubuntu:~/hadoop/hadoop/name/current$ ls

edits_0000000000000000001-0000000000000000001  fsimage_0000000000000000000.md5

edits_inprogress_0000000000000000002           seen_txid

fsimage_0000000000000000000                    VERSION

xiaoye@ubuntu:~/hadoop/hadoop/name/current$ vim VERSION

xiaoye@ubuntu:~/hadoop/hadoop/name/current$

#Fri Mar 30 00:14:41 PDT 2018

namespaceID=695608861

clusterID=CID-657e9540-2de9-43a2-bf91-199a4334b05a

cTime=0

storageType=NAME_NODE

blockpoolID=BP-583631310-127.0.1.1-1522394081528

layoutVersion=-59

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"VERSION" 7L, 200C      

在重新启动namenode

./hadoop/sbin/hadoop-daemons.sh start namenode

这时namenode还是没有启动成功，与是重复上面步骤，日志出现新的错误。

home/xiaoye/hadoop/journal/ns: NameNode has clusterId 'CID-b824b399-e941-4982-a618-745373

9d3d55' but storage has clusterId 'CID-657e9540-2de9-43a2-bf91-199a4334b05a'

于是还是修改上面的VERSION文件，把clusterId的值改成 storage的值，即可

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