DBA基础

查询NLS设置：select * from NLS_DATABASE_PARAMETERS;  

Flash_recovery_area目录例子：

/home/oracle/app/oracle/flash_recovery_area/

Alert log：

<background_dump_dest>/alert_<sid>.log。比如：/u01/app/oracle/diag/rdbms/orcl/orcl/trace/alert_orcl.log

Instance 启动步骤：

    startup nomount;  
    alter database mount;   |  STARTUP MOUNT  
    alter database open;    |  Startup  

启动时依次读取参数文件：

    spfileORACLE_SID.ora
    spfile.ora
    initORACLE_SID.ora

UNIX/Linux下，他们默认位于$ORACLE_HOME/dbs

使用PFile启动instance

STARTUP PFILE = /u01/oracle/dbs/init.ora

使用自定义SPFile启动

create /u01/oracle/dbs/spf_init.ora containing only:

 

   SPFILE = /u01/oracle/dbs/test_spfile.ora  

Then:

 STARTUP PFILE = /u01/oracle/dbs/spf_init.ora   

SPFile --> PFile

    CREATE PFILE FROM SPFILE;  
    CREATE PFILE='/u01/oracle/dbs/test_init.ora' FROM SPFILE='/u01/oracle/dbs/test_spfile.ora';  
    CREATE PFILE='/u01/oracle/dbs/test_init.ora' FROM MEMORY;  

PFile --> SPFile

    CREATE SPFILE FROM PFILE='/u01/oracle/dbs/init.ora';  
    CREATE SPFILE='/u01/oracle/dbs/test_spfile.ora' FROM PFILE='/u01/oracle/dbs/test_init.ora';  
    CREATE SPFILE FROM MEMORY;  

恢复Spfile至出厂设置
 

  ALTER SYSTEM RESET;