有时会遇到CDH集群的7180页面无法访问，通过命令查看服务发现：
1 service --status-all 2 cloudera-scm-server dead but pid file exists
删除pid文件：
1 rm -rf /var/run/cloudera-scm-server
然后启动服务cloudera-scm-server时会遇到过一段时间自己挂掉，并返回cloudera-scm-server dead but pid file exists的问题，主要是在cloudera-scm-server-db没有正常启动的情况，表现为如下情况：
1 [root@gyvm-4 data]# service cloudera-scm-server start 2 Starting cloudera-scm-server: [ OK ] 3 [root@gyvm-4 data]# 4 [root@gyvm-4 data]# service cloudera-scm-server status 5 cloudera-scm-server (pid 60761) is running... 6 [root@gyvm-4 data]# service cloudera-scm-server status 7 cloudera-scm-server (pid 60761) is running... 8 [root@gyvm-4 data]# service cloudera-scm-server status 9 cloudera-scm-server (pid 60761) is running... 10 [root@gyvm-4 data]# service cloudera-scm-server status 11 cloudera-scm-server dead but pid file exists
这时候想要完整重启cloudera-scm server-db/server，发现cloudera-scm-server-db无法重启
1 [root@gyvm-4 data]# service cloudera-scm-server-db stop 2 waiting for server to shut down............................................................... failed 3 pg_ctl: server does not shut down
无法停止server-db的原因是残留了一个pid文件，status显示不正确，删除该文件，通过status查看，server-db其实已经停止了。
1 [root@gyvm-4 data]# cd /var/lib/cloudera-scm-server-db/data 2 [root@gyvm-4 data]# service cloudera-scm-server-db status 3 pg_ctl: server is running (PID: 17378) 4 /usr/bin/postgres "-D" "/var/lib/cloudera-scm-server-db/data" 5 [root@gyvm-4 data]# rm postmaster.pid 6 rm: remove regular file `postmaster.pid'? y 7 [root@gyvm-4 data]# service cloudera-scm-server-db status 8 pg_ctl: no server running
再次开启server-db，成功，启动server，成功。
1 [root@gyvm-4 data]# service cloudera-scm-server-db start 2 DB initialization done. 3 waiting for server to start.... done 4 server started 5 [root@gyvm-4 data]# service cloudera-scm-server start 6 Starting cloudera-scm-server: [ OK ]
【结论】
究其原因，是cloudera-server-db没有正常启动，但是残留了pid文件postmaster.pid，所以查看cloudera-server-db状态时，显示有误，返回cloudera-server-db是启动的状态。在此基础上，每次启动cloudera-server就会失败。
转自：http://blog.csdn.net/c1990/article/details/54706330