EM 12c Location of alert log changed when database is started by multi-task job

 Environment

  Oracle Enterprise Manager:  Cloud Control 12.1.0.4

  Oracle database:   Enterprise Edition 11.2.0.3

  Oracle database home: /u01/app/oracle/product/11.2.0/dbhome_1

  ORACLE_BASE=/u01/app/oracle

  

Symptom

If database is started by sqlplus/srvctl from terminal, alert log file is

  /u01/app/oracle/diag/rdbms/db01/DB01/trace/alert_DB01.log

If database is started by multi-task job from OEM, alert log file is changed to

  /u01/app/oracle/product/11.2.0/dbhome_1/log/diag/rdbms/db01/DB01/trace/

Workaround

Use OS script to start database instead of EM.