Oracle 12C-CDB start-up process

To start DB12 as an example

' /as sysdba ' SQL 12.1. 0.2. 0 1 :1982, Oracle.  All rights reserved. Connected to an idle instance.

1.nomount Stage

Sql> startup Nomount;                         1174405120 bytesfixed Size                   2923680 bytesvariable Size              436208480 bytesdatabase buffers           721420288 Bytesredo buffers                13852672 Bytessql Select  from v$pdbs;no rows selected

2.mount Stage: Open control file, root and PDBs are all mount up

sql> ALTER DATABASE DB12 Mount;                Database altered. SQLSelect from v$pdbs;name                           open_mode---------------------------------------- Pdb$seed                       MOUNTEDPDB1                           MOUNTEDPDB2                           mounted

3.open Stage: Root is open, PDBs is still mounted state, seed PDB is read-only

sql> ALTER DATABASE DB12 Open;database altered. SQLSelect from v$pdbs;name                           open_mode---------------------------------------- Pdb$seed                       READ ONLYPDB1                           MOUNTEDPDB2                           mounted

4. Open PDB

 as sysdbaenter Password:Connected.SQL> alter pluggable database PDB1 open; Pluggable database altered. SQLSelect from V$pdbs;  NAME                           open_mode----------------------------------------PDB1                           READ writesql

Oracle 12C-CDB start-up process