我们知道,Oracle在启动过程中,需要读取参数文件(pfile/spfile)来创建实例.Oracle在启动过程中,寻找参数文件的顺序为:

spfile<sid>.ora,spfile.ora,init<sid>.ora.

而创建实例的过程中,Oracle需要的最少参数为一个,即db_name参数.

我们来看一个测试,启动一个任意设置的实例,本例ORACLE_SID=julia:

oracle@jumper dbs]$ export ORACLE_SID=julia
[oracle@jumper dbs]$ sqlplus "/ as sysdba"
SQL*Plus: Release 9.2.0.4.0
- Production on Mon May 8 11:08:36 2006
Copyright (c) 1982, 2002,
Oracle Corporation.  All rights reserved.
Connected to an idle instance.
SQL> startup nomount;
ORA-01078: failure in
processing system parameters
LRM-00109: could not open parameter
file '/opt/oracle/product/9.2.0/dbs/initjulia.ora'

Oracle最后检查的文件为initjulia.ora,让我们创建这个文件,然后数据库实例即可创建:

SQL> ! echo "db_name=julia" >
/opt/oracle/product/9.2.0/dbs/initjulia.ora

SQL> startup nomount;
ORACLE instance started.

Total System Global Area  
97588504 bytes
Fixed Size                  
451864 bytes
Variable Size             
46137344 bytes
Database Buffers          
50331648 bytes
Redo Buffers                
667648 bytes
 
我们可以看一下缺省的各类文件的存储地点:

SQL> show parameter dump_dest NAME TYPE VALUE
--------------- ----------------- --------
background_dump_dest string ?/rdbms/log
core_dump_dest string ?/dbs user_dump_dest
string ?/rdbms/log SQL> show parameter
control_files NAME TYPE VALUE
--------------- -----------------
control_files string ?/dbs/cntrl@.dbf

我们顺便看一下缺省的,警报日志中记录的信息:

oracle@jumper dbs]$ cat
$ORACLE_HOME/rdbms/log/alert_julia.log
Mon May  8 11:09:04 2006
Starting ORACLE instance (normal)
Mon May  8 11:09:04 2006
WARNING: EINVAL creating
segment of size 0x0000000006400000
fix shm parameters in /etc/system or equivalent
LICENSE_MAX_SESSION = 0
LICENSE_SESSIONS_WARNING = 0
SCN scheme 2
Using log_archive_dest parameter default value
LICENSE_MAX_USERS = 0
SYS auditing is disabled
Starting up ORACLE RDBMS Version: 9.2.0.4.0.
System parameters with non-default values:
  db_name                  = julia
PMON started with pid=2
DBW0 started with pid=3
LGWR started with pid=4
CKPT started with pid=5
SMON started with pid=6
RECO started with pid=7