Point-In-Time Pluggable Database Cloning With Oracle ASM Flex Disk Groups

 

Pluggable Database Cloning With Oracle ASM Flex Disk Group

The feature is introduced with oracle 18c and following are prerequisites to use this feature:-

•  Point-in-time database clones are supported only in Oracle ASM flex and extended disk groups.
•  Point-in-time database clones are supported only with Oracle Database 18c, version 18.1 or higher.
•  Point-in-time database clones require disk group compatibility attributes COMPATIBLE.ASM and COMPATIBLE.RDBMS be set to 18.0 or higher.
•  The source database (parent) must be a pluggable database. The database clone (child) created is a pluggable database under the same container database.

The Cloning is performed in 2 Steps:-

Preparing the Mirrored Copy

Splitting the Mirrored Copy and Creating the Database Clone.

Note: After preparing the  Mirrored Copy if you don't want to proceed for cloning you can drop the Mirrored Copy. The drop action discards all the changes performed by the ALTER PLUGGABLE DATABASE PREPARE SQL command. Action also triggers a rebalance on the appropriate disk group.

• Preparing the Mirrored Copy

SQL> show con_name
CON_NAME
------------------------------
CDB$ROOT

SQL> show pdbs

    CON_ID CON_NAME                       OPEN MODE  RESTRICTED
---------- ------------------------------ ---------- ----------
         2 PDB$SEED                       READ ONLY  NO
         3 PDB01                          READ WRITE NO

SQL> alter session set container=PDB01;
Session altered.

SQL>  ALTER PLUGGABLE DATABASE PREPARE MIRROR COPY PDB01_CLONE;
Pluggable database altered.

from ASM instance you can check the Prepare Status

SQL> SELECT * FROM V$ASM_DBCLONE_INFO;

GROUP_NUMBER DBCLONE_NAME    MIRRORCOPY_NAME DBCLONE_ST PARENT_DBNAME   PARENT_FILEGROU CON_ID
------------ --------------- --------------- ---------- --------------- --------------- ------
           1 DB_UNKNOWN      PDB01_CLONE     PREPARING  TST1T_PDB01     TST1T_PDB01          0

• Splitting the Mirrored Copy and Creating the Database Clone   

SQL>  SHOW CON_NAME
CON_NAME
------------------------------
PDB01

SQL> alter session set container=CDB$ROOT;
Session altered.

SQL> CREATE PLUGGABLE DATABASE PDB03 FROM PDB01 USING MIRROR COPY PDB01_CLONE ;
Pluggable database created.

If TDE is configured:-

In case if you have TDE you must specify the Keystore password  KEYSTORE IDENTIFIED BY password clause

SQL> CREATE PLUGGABLE DATABASE PDB03 FROM PDB01 USING MIRROR COPY PDB01_CLONE KEYSTORE IDENTIFIED BY keystore_password;
Pluggable database created.

From ASM instance you can check the Prepare Status:-

SQL> SELECT * FROM V$ASM_DBCLONE_INFO;

GROUP_NUMBER DBCLONE_NAME    MIRRORCOPY_NAME DBCLONE_STATUS  PARENT_DBNAME   PARENT_FILEGROU CON_ID
------------ --------------- --------------- --------------- --------------- --------------- ------
           1 TST1T_PDB03     PDB01_CLONE     SPLIT COMPLETED TST1T_PDB01     TST1T_PDB01          0

SQL> show pdbs;

CON_ID CON_NAME                       OPEN MODE  RESTRICTED
---------- ------------------------------ ---------- ----------
         2 PDB$SEED                       READ ONLY  NO
         3 PDB01                          READ WRITE NO
         5 PDB03                          MOUNTED

SQL> alter session set container=PDB03;
Session altered.

SQL> alter pluggable database PDB03 open;
Pluggable database altered.

SQL> show pdbs;

CON_ID CON_NAME                       OPEN MODE  RESTRICTED
---------- ------------------------------ ---------- ----------
         5 PDB03                          READ WRITE NO

• Dropping the Prepared Mirror Copy

After preparing the mirrored copy if you don't want to proceed with cloning you can simply drop the mirror copy

SQL> alter session set container=PDB01;

SQL> ALTER PLUGGABLE DATABASE DROP MIRROR COPY PDB01_CLONE;

Note: You can not drop the mirror copy once you have completed the cloning. If you attempt to drop the mirror copy you will receive the following error.

ORA-59024: dropping mirror copy 'PDB01_CLONE' in disk group 'DATA' failed as
the file split is complete