日志分类
oracle数据库日志分为告警日志（alert）和跟踪日志（trace）两类，可通过查询系统参数获取日志文件存放路径：
SQL> show parameter dump
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
background_core_dump string partial
background_dump_dest string /opt/oracle/diag/rdbms/mmsgdb/
mmsgdb/trace
core_dump_dest string /opt/oracle/diag/rdbms/mmsgdb/
mmsgdb/cdump
max_dump_file_size string unlimited
shadow_core_dump string partial
user_dump_dest string /opt/oracle/diag/rdbms/mmsgdb/
mmsgdb/trace
监控数据库的操作
定期监控数据库的操作很重要，因为这样做，不仅可以提前通知管理员数据库存在的错误，让管理员提高警惕，同时也可以让管理员更好的理解数据库的操作。
监控数据库的错误与告警
使用跟踪文件和告警日志监控数据库的操作。
当前oracle数据库的跟踪和告警日志以XML文件进行维护，可以使用任意编辑器来查看文本格式的告警日志，也可以使用ADRCI应用程序来查看XML格式的告警日志，同时，在ADRCI应用程序中，可以改变当前的ADR位置，也可以使用show home命令来显示所有的ADR位置，适应show alert 命令来显示告警日志，操作如下：
oracle@mmsg:~> whoami
oracle
oracle@mmsg:~> adrci
ADRCI: Release 11.1.0.7.0 - Production on 星期三 5月 19 16:46:21 2010
Copyright (c) 1982, 2007, Oracle. All rights reserved.
ADR base = "/opt/oracle"
adrci> show home
ADR Homes:
diag/rdbms/mmsgdb/mmsgdb
diag/tnslsnr/mmsg/listener
adrci> show homes
ADR Homes:
diag/rdbms/mmsgdb/mmsgdb
diag/tnslsnr/mmsg/listener
adrci> show homepath
ADR Homes:
diag/rdbms/mmsgdb/mmsgdb
diag/tnslsnr/mmsg/listener
adrci> show alert -tail
DIA-48449: Tail alert can only apply to single ADR home
adrci> exit
oracle@mmsg:~> oerr dia 48449
48449, 00000, "Tail alert can only apply to single ADR home"
// *Document: YES
// *Cause: There are multiple homes in the current setting
// *Action: Use command SET HOMEPATH to set a single home
oracle@mmsg:~> adrci
ADRCI: Release 11.1.0.7.0 - Production on 星期三 5月 19 16:46:57 2010
Copyright (c) 1982, 2007, Oracle. All rights reserved.
ADR base = "/opt/oracle"
adrci> set homepath diag/tnslsnr/mmsg/listener
adrci> show alert -tail
2010-05-19 16:47:08.815000 +08:00
19-5月 -2010 16:47:08 * (CONNECT_DATA=(SID=mmsgdb)(CID=(PROGRAM=)(HOST=__jdbc__)(USER=))) * (ADDRESS=(PROTOCOL=tcp)(HOST=10.137.49.114)(PORT=25644)) * establish * mmsgdb * 0
2010-05-19 16:47:11.377000 +08:00
19-5月 -2010 16:47:11 * service_update * mmsgdb * 0
2010-05-19 16:47:13.132000 +08:00
19-5月 -2010 16:47:13 * (CONNECT_DATA=(SID=mmsgdb)(CID=(PROGRAM=)(HOST=__jdbc__)(USER=))) * (ADDRESS=(PROTOCOL=tcp)(HOST=10.137.49.114)(PORT=35728)) * establish * mmsgdb * 0
19-5月 -2010 16:47:13 * (CONNECT_DATA=(SID=mmsgdb)(CID=(PROGRAM=)(HOST=__jdbc__)(USER=))) * (ADDRESS=(PROTOCOL=tcp)(HOST=10.137.49.114)(PORT=58040)) * establish * mmsgdb * 0
19-5月 -2010 16:47:13 * (CONNECT_DATA=(SID=mmsgdb)(CID=(PROGRAM=)(HOST=__jdbc__)(USER=))) * (ADDRESS=(PROTOCOL=tcp)(HOST=10.137.49.114)(PORT=7921)) * establish * mmsgdb * 0
19-5月 -2010 16:47:13 * (CONNECT_DATA=(SID=mmsgdb)(CID=(PROGRAM=)(HOST=__jdbc__)(USER=))) * (ADDRESS=(PROTOCOL=tcp)(HOST=10.137.49.114)(PORT=10131)) * establish * mmsgdb * 0
19-5月 -2010 16:47:13 * (CONNECT_DATA=(SID=mmsgdb)(CID=(PROGRAM=)(HOST=__jdbc__)(USER=))) * (ADDRESS=(PROTOCOL=tcp)(HOST=10.137.49.114)(PORT=21875)) * establish * mmsgdb * 0
19-5月 -2010 16:47:13 * (CONNECT_DATA=(SID=mmsgdb)(CID=(PROGRAM=)(HOST=__jdbc__)(USER=))) * (ADDRESS=(PROTOCOL=tcp)(HOST=10.137.49.114)(PORT=10084)) * establish * mmsgdb * 0
19-5月 -2010 16:47:13 * (CONNECT_DATA=(SID=mmsgdb)(CID=(PROGRAM=)(HOST=__jdbc__)(USER=))) * (ADDRESS=(PROTOCOL=tcp)(HOST=10.137.49.114)(PORT=22965)) * establish * mmsgdb * 0
19-5月 -2010 16:47:13 * (CONNECT_DATA=(SID=mmsgdb)(CID=(PROGRAM=)(HOST=__jdbc__)(USER=))) * (ADDRESS=(PROTOCOL=tcp)(HOST=10.137.49.114)(PORT=2304)) * establish * mmsgdb * 0
19-5月 -2010 16:47:13 * (CONNECT_DATA=(SID=mmsgdb)(CID=(PROGRAM=)(HOST=__jdbc__)(USER=))) * (ADDRESS=(PROTOCOL=tcp)(HOST=10.137.49.114)(PORT=15243)) * establish * mmsgdb * 0
19-5月 -2010 16:47:13 * (CONNECT_DATA=(SID=mmsgdb)(CID=(PROGRAM=)(HOST=__jdbc__)(USER=))) * (ADDRESS=(PROTOCOL=tcp)(HOST=10.137.49.114)(PORT=3562)) * establish * mmsgdb * 0
2010-05-19 16:47:14.379000 +08:00
19-5月 -2010 16:47:14 * service_update * mmsgdb * 0
adrci> exit
oracle@mmsg:~>
