Oracle Database 11gR2 OEM troubleshooting case

Oracle Database 11gR2 OEM troubleshooting case

If the customer's OEM fails, the logon page is displayed as follows:

Checking the database status and services is normal.
The best way to solve the problem is, of course, to view the background log and report the error, where is the EM Log? Obviously:
[Oracle @ dm01db01 trace] $ emctl status dbconsole
Oracle Enterprise Manager 11g Database Control Release 11.2.0.4.0
Copyright (c) 1996,201 3 Oracle Corporation. All rights reserved.
Https: // xxx: 1158/em/console/aboutApplication
Oracle Enterprise Manager 11g is running.
------------------------------------------------------------------
Logs are generated in directory/u01/app/oracle/product/11.2.0.4/dbhome_1/dm01db01_tequdb/sysman/log

When you start and view the em status, the last line limits the location of the OEM log and switches to the log directory. For example:
Total 98016
-Rw-r ----- 1 oracle oinstall 3578020 Feb 9 emagentfetchlet. log
-Rw-r ----- 1 oracle oinstall 3578020 Feb 9 emagentfetchlet. trc
-Rw-r ----- 1 oracle oinstall 16736 Feb 9 emagent. log
-Rw-r ----- 1 oracle oinstall 426000 Feb 9 emagent_perl.trc
-Rw-r ----- 1 oracle oinstall 1247726 Feb 9 emagent. trc
-Rw-r ----- 1 oracle oinstall 4194367 Feb 8 emagent. trc.1
-Rw-r ----- 1 oracle oinstall 1302 Feb 7 emctl. msg
-Rw-r ----- 1 oracle oinstall 544351 Feb 9 emdb. nohup
-Rw-r ----- 1 oracle oinstall 0 Jul 29 2014 emdctl. log
-Rw-r ----- 1 oracle oinstall 14412 Feb 9 emdctl. trc
-Rw-r ----- 1 oracle oinstall 15773411 Feb 9 emoms. log
-Rw-r ----- 1 oracle oinstall 20001650 Feb 9 emoms. log.1
-Rw-r ----- 1 oracle oinstall 720617 Feb 9 emoms. trc
-Rw-r ----- 1 oracle oinstall 5000504 Feb 9 emoms. trc.1
-Rw-r ----- 1 oracle oinstall 5003162 Feb 9 emoms. trc.10
-Rw-r ----- 1 oracle oinstall 5001267 Feb 9 emoms. trc.2
-Rw-r ----- 1 oracle oinstall 5003639 Feb 9 emoms. trc.3
-Rw-r ----- 1 oracle oinstall 5000450 Feb 9 emoms. trc.4
-Rw-r ----- 1 oracle oinstall 5000447 Feb 9 emoms. trc.5
-Rw-r ----- 1 oracle oinstall 5002270 Feb 9 emoms. trc.6
-Rw-r ----- 1 oracle oinstall 5002974 Feb 9 emoms. trc.7
-Rw-r ----- 1 oracle oinstall 5000153 Feb 9 emoms. trc.8
-Rw-r ----- 1 oracle oinstall 5000000 Feb 9 emoms. trc.9
-Rw-r ----- 1 oracle oinstall 0 Jul 29 2014 nfsPatchPlug. log
Drwxr ----- 2 oracle oinstall 4096 Jul 29 2014 pafLogs/
-Rw-r ----- 1 oracle oinstall 0 Jul 29 2014 patchAgtStPlugin. log
-Rw-r ----- 1 oracle oinstall 10591 Jul 29 2014 secure. log

Among them, emoms. log records most of the OEM logs. You can view the logs and find the following error:
......
20:29:14, 242 [HTTPThreadGroup-10] WARN jdbc. ConnectionCache _ getConnection.353-Got a fatal exeption when getting a connection; Error code = 17002; Cleaning up cache and retrying
20:29:14, 242 [HTTPThreadGroup-10] ERROR conn. ConnectionService verifyRepositoryEx.891-Invalid Connection Pool. ERROR = Io exception: Unknown host specified
20:29:14, 243 [HTTPThreadGroup-10] WARN jdbc. ConnectionCache _ getConnection.352-Io exception: Unknown host specified
Java. SQL. SQLException: Io exception: Unknown host specified
......

The error is very obvious, and the host cannot be parsed. The host here should be scan-name, and all attempts to ping <scan-name> and nslookup <scan-name> fail, later I learned that the customer's DNS server was faulty, So I temporarily added one of the IP addresses corresponding to scan-name to the/etc/hosts file, and restarted the oem to restore the normal operation.

In addition, the OEM configuration files are stored in the $ ORACLE_HOME/sysman/config directory.

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