class="tags" href="/tags/ORACLE.html" title=oracle>oracleclass="tags" href="/tags/ShuJuKu.html" title=数据库>数据库启动的四个阶段࿰c;见下图:

c="http://hi.csdn.net/attachment/201203/3/0_1330768197kfZ0.gif" alt="" />

1. class="tags" href="/tags/ShuJuKu.html" title=数据库>数据库处于SHUTDOWN状态

在此种状态࿰c;class="tags" href="/tags/ShuJuKu.html" title=数据库>数据库处于停止状态。不能接受外界数据请求。使用操作系统命令ps –ef | grep ora看不到任何class="tags" href="/tags/ShuJuKu.html" title=数据库>数据库进程的存在。

2. class="tags" href="/tags/ShuJuKu.html" title=数据库>数据库处于NOMOUNT状态

在此种状态࿰c;class="tags" href="/tags/ShuJuKu.html" title=数据库>数据库后台进程已经建立。并根据参数文件中关于SGA的相关参数࿰c;建立共享内存区和缺省的class="tags" href="/tags/ORACLE.html" title=oracle>oracleclass="tags" href="/tags/ShuJuKu.html" title=数据库>数据库进程。并同时检查相关初始化参数的正确性。

使用操作系统命令可以考到相应的进程。ps –ef | grep ora_  并且使用ipcs –m命令可以看到以class="tags" href="/tags/ORACLE.html" title=oracle>oracle用户建立起来的共享内存区。

class="tags" href="/tags/ORACLE.html" title=oracle>oracle@db1:~> class="tags" href="/tags/SQL.html" title=sql>sqlplus / as sysdba


SQL*Plus: Release 10.2.0.1.0 - Production on Sat Mar 3 22:48:27 2012


Copyright (c) 1982, 2005, Oracle.  All rights reserved.


Connected to an idle instance.


SQL> startup nomount;
ORACLE instance started.


Total System Global Area  167772160 bytes
Fixed Size                  1218316 bytes
Variable Size             104859892 bytes
Database Buffers           58720256 bytes
Redo Buffers                2973696 bytes
SQL> 

查看进程状态.

class="tags" href="/tags/ORACLE.html" title=oracle>oracle@db1:~> ps -ef | grep ora_
class="tags" href="/tags/ORACLE.html" title=oracle>oracle 3626 1 0 22:48 ? 00:00:00 ora_pmon_orcl1
class="tags" href="/tags/ORACLE.html" title=oracle>oracle 3628 1 0 22:48 ? 00:00:00 ora_psp0_orcl1
class="tags" href="/tags/ORACLE.html" title=oracle>oracle 3630 1 0 22:48 ? 00:00:00 ora_mman_orcl1
class="tags" href="/tags/ORACLE.html" title=oracle>oracle 3632 1 0 22:48 ? 00:00:00 ora_dbw0_orcl1
class="tags" href="/tags/ORACLE.html" title=oracle>oracle 3634 1 0 22:48 ? 00:00:00 ora_lgwr_orcl1
class="tags" href="/tags/ORACLE.html" title=oracle>oracle 3636 1 0 22:48 ? 00:00:00 ora_ckpt_orcl1
class="tags" href="/tags/ORACLE.html" title=oracle>oracle 3638 1 0 22:48 ? 00:00:00 ora_smon_orcl1
class="tags" href="/tags/ORACLE.html" title=oracle>oracle 3640 1 0 22:48 ? 00:00:00 ora_reco_orcl1
class="tags" href="/tags/ORACLE.html" title=oracle>oracle 3642 1 0 22:48 ? 00:00:00 ora_cjq0_orcl1
class="tags" href="/tags/ORACLE.html" title=oracle>oracle 3644 1 0 22:48 ? 00:00:00 ora_mmon_orcl1
class="tags" href="/tags/ORACLE.html" title=oracle>oracle 3646 1 0 22:48 ? 00:00:00 ora_mmnl_orcl1
class="tags" href="/tags/ORACLE.html" title=oracle>oracle 3648 1 0 22:48 ? 00:00:00 ora_d000_orcl1
class="tags" href="/tags/ORACLE.html" title=oracle>oracle 3650 1 0 22:48 ? 00:00:00 ora_s000_orcl1
class="tags" href="/tags/ORACLE.html" title=oracle>oracle 3669 3652 0 22:50 pts/2 00:00:00 grep ora_
class="tags" href="/tags/ORACLE.html" title=oracle>oracle@db1:~>
class="tags" href="/tags/ORACLE.html" title=oracle>oracle@db1:~> ipcs -m

------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0xe835086c 458764 class="tags" href="/tags/ORACLE.html" title=oracle>oracle 640 171966464 14

class="tags" href="/tags/ORACLE.html" title=oracle>oracle@db1:~>

3. class="tags" href="/tags/ShuJuKu.html" title=数据库>数据库处于MOUNT状态

class="tags" href="/tags/ShuJuKu.html" title=数据库>数据库读取控制文件中的内容࿰c;并按照控制文件中指定的参数找到相应的数据文件࿰c;并启动class="tags" href="/tags/ShuJuKu.html" title=数据库>数据库的归档或非归档状态。

class="tags" href="/tags/ShuJuKu.html" title=数据库>数据库在此状态检查各个数据文件的一致性。如果出现数据文件损坏࿰c;要求用户进行恢复。

SQL> startup mount;
ORACLE instance started.

Total System Global Area 167772160 bytes
Fixed Size 1218316 bytes
Variable Size 104859892 bytes
Database Buffers 58720256 bytes
Redo Buffers 2973696 bytes
Database mounted.

4. class="tags" href="/tags/ShuJuKu.html" title=数据库>数据库处于OPEN状态

class="tags" href="/tags/ShuJuKu.html" title=数据库>数据库在此状态检查各个数据文件的一致性。如果出现数据文件损坏࿰c;要求用户进行恢复。

SQL> startup;
ORACLE instance started.

Total System Global Area 167772160 bytes
Fixed Size 1218316 bytes
Variable Size 104859892 bytes
Database Buffers 58720256 bytes
Redo Buffers 2973696 bytes
Database mounted.
Database opened.
SQL>

5.改变class="tags" href="/tags/ShuJuKu.html" title=数据库>数据库的状态

SQL> startup nomount;
ORACLE instance started.


Total System Global Area  167772160 bytes
Fixed Size                  1218316 bytes
Variable Size              96471284 bytes
Database Buffers           67108864 bytes
Redo Buffers                2973696 bytes
SQL> alter class="tags" href="/tags/DATABASE.html" title=database>database mount;


Database altered.


SQL> alter class="tags" href="/tags/DATABASE.html" title=database>database open;


Database altered.