1Z0-031.3 - 5. 诊断文件(alert files, backgroud trace files, user trace files).doc

Diagnostic FilesDiagnostic files are a means to capture information about the databases activities.Types:- alertSID.log file : Information for day-to-day operation of the database- Background trace files : Vital information when background processes, such as SMON, PMON, DBWn, and others fail.- User trace files : Vital information for fatal user errors or user forced traced files.Alert Log FileThe alertSID.log file records the commands and Results of major events while the database is operational. 这主要包括Oracle的内部错误、数据块损坏错误、特权用户操作（例如启动例程、关闭例程、备份和恢复等）、数据库物理结构变化等信息。其信息由服务器进程和后台进程DBWR、LGWR写入。- Each entry has a time stamp associated with it.- The DBA manages the alertSID.log file.- Its location is defined by BACKGROUND_DUMP_DEST.The alert log file keeps a record of the following information:- When the database was started or shut down- A list of all non-default initialization parameters- The startup of background processes- The thread being used by the instance- The log sequence number LGWR is writing to- Information regarding a log switch- Creation of tablespaces and undo segments- Alter statements that have been issued- Information regarding error messages such as ORA-600 and extent errors.Background Trace Files- They are created when a background process encounters an errors- Their location is defined by BACKGROUND_DUMP_DESTUser Trace File- It can also be generated by a you or a server process.- Its location is defined by USER_DUMP_DEST.- Its size is defined by MAX_DUMP_FILE_SIZE and defaults to 10M.Enabling or Disabling User TracingUser tracing is enabled or disabled at the session or instance level by using the following commands and parameter:- Session level using the ALTER SESSION command:- ALTER SESSION SET SQL_TRACE = TRUE;- Session level by executing DBMS procedure:- dbms_system.SET_