在ORACLE 11g 以及ORACLE 12c中，告警日志文件的位置有了变化。主要是因为引入了ADR(Automatic Diagnostic Repository（自动诊断仓库）:一个存放数据库诊断日志、跟踪文件的目录，关于ADR对应的目录位置可以通过查看v$diag_info系统视图。
12c环境下查询，alert日志并不在bdump目录下，需要通过v$diag_info视图查询
Oracle用户及grid用户，通过切换用户查看各自的日志。
SQL> show parameter dump
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
background_core_dump string partial
background_dump_dest string /u01/app/oracle/product/12.2.0
/db_1/rdbms/log
core_dump_dest string /u01/app/oracle/diag/rdbms/orc
l/racdb11/cdump
max_dump_file_size string unlimited
shadow_core_dump string partial
user_dump_dest string /u01/app/oracle/product/12.2.0
/db_1/rdbms/logadump:审计信息
bdump：后台进程trace和alert log,就是说alert_sid.log日志也存在此处
cdump：core trace,一般是用来日志应用程序的 除非数据库出了问题 否则基本上不会有什么信息
dpdump ：是存放一些登录信息的
pfile ：初始化参数文件 initSID
udump ：user dump，前台手动trace的 比如sql trace之后session的trace文件
SQL> set linesize 999
SQL> select * from v$diag_info;
INST_ID NAME VALUE CON_ID
---------- ---------------------------------------------------------------- -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ----------
1 Diag Enabled TRUE 0
1 ADR Base /u01/app/oracle 0
1 ADR Home /u01/app/oracle/diag/rdbms/orcl/racdb11 0
1 Diag Trace /u01/app/oracle/diag/rdbms/orcl/racdb11/trace 0
1 Diag Alert /u01/app/oracle/diag/rdbms/orcl/racdb11/alert 0
1 Diag Incident /u01/app/oracle/diag/rdbms/orcl/racdb11/incident 0
1 Diag Cdump /u01/app/oracle/diag/rdbms/orcl/racdb11/cdump 0
1 Health Monitor /u01/app/oracle/diag/rdbms/orcl/racdb11/hm 0
1 Default Trace File /u01/app/oracle/diag/rdbms/orcl/racdb11/trace/racdb11_ora_58690.trc 0
1 Active Problem Count 1 0
1 Active Incident Count 1 0
Diag Trace对应的目录为文本格式的告警日志文件所在的目录,
[oracle@jydb1 trace]$ pwd
/u01/app/oracle/diag/rdbms/orcl/racdb11/trace
[oracle@jydb1 trace]$ tail -n10 alert_racdb11.log
reflect the new space.
4. Delete unnecessary files using RMAN DELETE command. If an operating
system command was used to delete files, then use RMAN CROSSCHECK and
DELETE EXPIRED commands.
************************************************************************
2018-08-08T17:31:11.405609+08:00
Errors in file /u01/app/oracle/diag/rdbms/orcl/racdb11/trace/racdb11_arc1_64025.trc:
ORA-19809: 超出了恢复文件数的限制
ORA-19804: 无法回收 182452224 字节磁盘空间 (从 19368247296 字节限制中)
ARC1: Error 19809 Creating archive log file to '+FRA'
而Diag Alert对应的目录为XML格式的警告日志(对应为log_x.xml)
[oracle@jydb1 alert]$ pwd
/u01/app/oracle/diag/rdbms/orcl/racdb11/alert
[oracle@jydb1 alert]$ tail -n20 log.xml
con_id='1' con_name='CDB$ROOT'>
<txt>************************************************************************
</txt>
</msg>
<msg time='2018-08-08T17:33:00.990+08:00' org_id='oracle' comp_id='rdbms'
type='UNKNOWN' level='16' host_id='jydb1'
host_addr='192.168.12.95' pid='64027' con_uid='1'
con_id='1' con_name='CDB$ROOT'>
<txt>Errors in file /u01/app/oracle/diag/rdbms/orcl/racdb11/trace/racdb11_arc2_64027.trc:
ORA-19809: 超出了恢复文件数的限制
ORA-19804: 无法回收 182452224 字节磁盘空间 (从 19368247296 字节限制中)
</txt>
</msg>
<msg time='2018-08-08T17:33:00.990+08:00' org_id='oracle' comp_id='rdbms'
type='UNKNOWN' level='16' host_id='jydb1'
host_addr='192.168.12.95' pid='64027' con_uid='1'
con_id='1' con_name='CDB$ROOT'>
<txt>ARC2: Error 19809 Creating archive log file to '+FRA'
</txt>
</msg>而在oracle 11g环境下可以直接通过查询bdump参数，来找到alert日志位置
SQL> show parameter background_dump_dest;
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
background_dump_dest string /u01/app/oracle/product/12.2.0
/db_1/rdbms/log12c监听位置没有改变
cd $ORACLE_HOME/network/admin
[oracle@localhost admin]$ ls
listener.ora samples shrept.lst sqlnet.ora tnsnames.ora