以启动DB12为例子

 

$ sqlplus '/as sysdba'SQL*Plus: Release 12.1.0.2.0 Production on Sun Nov 1 15:48:15 2015Copyright (c) 1982, 2014, Oracle.  All rights reserved.Connected to an idle instance.

1.nomount阶段

SQL> startup nomount;                        ORACLE instance started.Total System Global Area 1174405120 bytesFixed Size                  2923680 bytesVariable Size             436208480 bytesDatabase Buffers          721420288 bytesRedo Buffers               13852672 bytesSQL> select name,open_mode from v$pdbs;no rows selected

2.mount阶段：打开控制文件，Root和pdbs都被mount起来

SQL> alter database db12 mount;                Database altered.SQL> select name,open_mode from v$pdbs;NAME                           OPEN_MODE------------------------------ ----------PDB$SEED                       MOUNTEDPDB1                           MOUNTEDPDB2                           MOUNTED

3.open阶段：root被打开，pdbs仍然是mounted状态，seed pdb处于只读状态

SQL> alter database db12 open;Database altered.SQL> select name,open_mode from v$pdbs;NAME                           OPEN_MODE------------------------------ ----------PDB$SEED                       READ ONLYPDB1                           MOUNTEDPDB2                           MOUNTED

4.打开PDB

SQL> connect sys@pdb1 as sysdbaEnter password: Connected.SQL> alter pluggable database pdb1 open;Pluggable database altered.SQL> select name,open_mode from v$pdbs;  NAME                           OPEN_MODE------------------------------ ----------PDB1                           READ WRITESQL>