Oracle by Example brandingManaging CDB Fleets

section 0Before You Begin


This 15-minute tutorial shows you how to define a CDB as the CDB lead within a CDB fleet and how to define other CDBs as members of the CDB fleet.

Background

Oracle Database 18c introduces the CDB fleet concept, which is a collection of different CDBs that can be managed as one logical CDB to provide the underlying infrastructure for massive scalability and centralized management of many CDBs.

This technique uses database properties setting and database links.

What Do You Need?

  • Oracle Database 18c installed
  • Three container databases (CDB) and a pluggable database (PDB) in two of the CDBs: ORCL CDB as the CDB lead, cdb1 and cdb2 as CDB members, PDB1 PDB in cdb1 CDB and PDB2 PDB in cdb2 CDB

section 1Set the CDB Lead in the CDB Fleet

  1. Log in to ORCL CDB as SYS. This session is called Session1. 
    export ORACLE_SID=ORCL
sqlplus / AS SYSDBA
  2. Verify that the CDB is not already a CDB lead before you set ORCL as the CDB lead in the CDB fleet. 
    SELECT property_name, property_value FROM database_properties
WHERE  property_name LIKE 'LEAD%';

PROPERTY_NAME      PROPERTY_VALUE
------------------ --------------------
LEAD_CDB           FALSE
    There is another way to verify this. 
    SELECT sys_context('userenv', 'is_lead_cdb') LEAD_CDB FROM dual;
 
LEAD_CDB
--------------------------------------------------------------------
NO
  3. Set ORCL as the CDB lead in the CDB fleet. 
    ALTER DATABASE SET LEAD_CDB = true;
  4. Verify that ORCL is the CDB lead in the CDB fleet. 
    SELECT sys_context('userenv', 'is_lead_cdb') LEAD_CDB FROM dual;
 
LEAD_CDB
--------------------------------------------------------------------
YES
  5. View the same information of the lead role of the CDB in the alert log file. 
    $ tail /u01/app/oracle/diag/rdbms/orcl/ORCL/trace/a*
...
2017-12-12T03:37:33.595312+00:00
ALTER DATABASE SET LEAD_CDB = true
2017-12-12T03:37:33.595487+00:00
The role of current CDB in the Fleet is: LEAD
Completed: ALTER DATABASE SET LEAD_CDB = true
  6. Grant the appropriate privileges to the common user in the CDB lead that will be used for future CDB members to exchange with the CDB lead through database links. 
    GRANT sysoper TO system CONTAINER=ALL;

section 2Define CDBs as Members of the Fleet

  1. In another terminal window, log in to cdb1 as SYS. This session is called Session2. 
    export ORACLE_SID=cdb1
sqlplus / AS SYSDBA
  2. Set cdb1 as a member of the fleet. 
    SELECT sys_context('userenv', 'is_member_cdb') MEMBER_CDB FROM dual;
  
MEMBER_CDB
------------
NO
  3. Use a common user in the CDB member identical to a common user in the CDB lead that will be used to create the fixed user database link. 
    CREATE PUBLIC DATABASE LINK lorcl CONNECT TO system IDENTIFIED BY password
       USING 'ORCL';
  4. Set the CDB as a member of the fleet. 
    ALTER DATABASE SET LEAD_CDB_URI = 'dblink:lorcl';
  5. Verify that cdb1 is a CDB member in the CDB fleet. 
    SELECT sys_context('userenv', 'is_member_cdb') MEMBER_CDB FROM dual;
  
MEMBER_CDB
------------
YES
  6. View the same information of the member role of the CDB in the alert log file. 
    $ tail /u01/app/oracle/diag/rdbms/cdb1/cdb1/trace/a*
...
2017-12-12T04:15:00.352901+00:00
ALTER DATABASE SET LEAD_CDB_URI = 'dblink:lorcl'
2017-12-12T04:15:00.423278+00:00
The role of current CDB in the Fleet is: MEMBER
Completed: ALTER DATABASE SET LEAD_CDB_URI = 'dblink:lorcl'
  7. List the PDBs of the CDB member. 
    SHOW PDBS

    CON_ID CON_NAME                       OPEN MODE  RESTRICTED
---------- ------------------------------ ---------- ----------
         2 PDB$SEED                       READ ONLY  NO
         3 PDB1                           READ WRITE NO
  8. In Session1, list all PDBs of all CDBs in the fleet. 
    SHOW PDBS

    CON_ID CON_NAME                       OPEN MODE  RESTRICTED
---------- ------------------------------ ---------- ----------
         2 PDB$SEED                       READ ONLY  NO
         3 PDB_ORCL                       READ WRITE NO
         5 PDB1                           MOUNTED
    Why is the OPEN_MODE value of the pdb1 member MOUNTED in the CDB lead whereas it is OPENED in cdb1? Members can only be opened in the CDB where they physically exist. 
    SELECT pdb_id, pdb_name, status, is_proxy_pdb "IS_PROXY_PDB" FROM dba_pdbs;

    PDB_ID PDB_NAME STATUS  IS_PROXY_PDB
---------- -------- ------- ------------
         3 PDB_ORCL NORMAL  NO
         2 PDB$SEED NORMAL  NO
         4 cdb1     STUB    YES
         5 PDB1     STUB    YES
    The STUB value in the STATUS column defines the CDB and its PDBs as members in the fleet.  After you configure the CDB fleet, PDB information from the various CDB members including the CDB member is synchronized with the lead CDB. All PDBs in the CDB members are now “visible” in the lead CDB, enabling you to access the PDBs in the fleet as a single, logical CDB from the lead CDB.
  9. In another terminal window, log in to cdb2 as SYS. This session is called Session3, 
    export ORACLE_SID=cdb2
sqlplus / AS SYSDBA
  10. Repeat the steps 2 to 5 in order to set cdb2 as another member of the fleet. 
    SELECT sys_context('userenv', 'is_member_cdb') MEMBER_CDB FROM dual;
  
MEMBER_CDB
-----------
NO
  11. Use a common user in the CDB member identical to a common user in the CDB lead that will be used to create the fixed user database link. 
    CREATE PUBLIC DATABASE LINK lorcl CONNECT TO system IDENTIFIED BY password
       USING 'ORCL';
  12. Set the CDB as a member of the fleet. 
    ALTER DATABASE SET LEAD_CDB_URI = 'dblink:lorcl';
  13. Verify that cdb2 is a CDB member in the CDB fleet. 
    SELECT sys_context('userenv', 'is_member_cdb') MEMBER_CDB FROM dual;
  
MEMBER_CDB
------------
YES
  14. View the same information of the member role of the CDB in the alert log file. 
    $ tail /u01/app/oracle/diag/rdbms/cdb2/cdb2/trace/a*
...
2017-12-12T04:20:00.352901+00:00
ALTER DATABASE SET LEAD_CDB_URI = 'dblink:lorcl'
2017-12-12T04:20:00.423999+00:00
The role of current CDB in the Fleet is: MEMBER
Completed: ALTER DATABASE SET LEAD_CDB_URI = 'dblink:lorcl'
  15. List the PDBs of the CDB member. 
    SHOW PDBS

    CON_ID CON_NAME                       OPEN MODE  RESTRICTED
---------- ------------------------------ ---------- ----------
         2 PDB$SEED                       READ ONLY  NO
         3 PDB2                           READ WRITE NO
  16. In Session1, check that PDB information from the CDB members is synchronized with the CDB lead. Read the list from code1. 
    SELECT name, open_mode, member_cdb "MEMBER_CDB" FROM v$containers;
  17. Read the list from another view. See the result from code2. 
    SELECT pdb_id, pdb_name, status, is_proxy_pdb "IS_PROXY_PDB" FROM dba_pdbs;

section 3Unset the CDB Lead

  1. You decide to deactivate the CDB lead. In Session1, execute the following ALTER DATABASE statement. 
    ALTER DATABASE SET LEAD_CDB = false;
    Does it deactivate CDB members? No, it does not because the membership property is still maintained in CDB members. The CDB members can be reattached to the CDB lead ORCL once ORCL will have been reset as the lead of the fleet.
  2. Verify in Session2. 
    SELECT sys_context('userenv', 'is_member_cdb') MEMBER_CDB FROM dual;
 
MEMBER_CDB
------------
YES
  3. In Session1, reset the CDB lead. 
    ALTER DATABASE SET LEAD_CDB = true;
  4. Observe that the members of the fleet reappear in the list of monitored PDBs once they get reregistered to the lead. 
    SELECT pdb_id, pdb_name, status, is_proxy_pdb "IS_PROXY_PDB" FROM dba_pdbs;

    PDB_ID PDB_NAME STATUS  IS_PROXY_PDB
---------- -------- ------- ------------
         3 PDB_ORCL NORMAL  NO
         2 PDB$SEED NORMAL  NO
  5. Repeat the query to see the CDB members reattaching. 
    SELECT pdb_id, pdb_name, status, is_proxy_pdb "IS_PROXY_PDB" FROM dba_pdbs;

    PDB_ID PDB_NAME STATUS  IS_PROXY_PDB
---------- -------- ------- ------------
         3 PDB_ORCL NORMAL  NO
         2 PDB$SEED NORMAL  NO
         4 cdb1     STUB    YES
         5 PDB1     STUB    YES
  6. Repeat the query to see the CDB members reattaching. 
    SELECT pdb_id, pdb_name, status, is_proxy_pdb "IS_PROXY_PDB" FROM dba_pdbs;

    PDB_ID PDB_NAME STATUS  IS_PROXY_PDB
---------- -------- ------- ------------
         3 PDB_ORCL NORMAL  NO
         2 PDB$SEED NORMAL  NO
         4 cdb1     STUB    YES
         5 PDB1     STUB    YES
         6 cdb2     STUB    YES
         7 PDB2     STUB    YES

section 4Unset a CDB Member

  1. You decide to release the membership of cdb1 from the fleet. You may prefer to associate it to another fleet. Go to Session2. 
    ALTER DATABASE SET LEAD_CDB_URI = '';
  2. In Session1, check that the CDB lead does not monitor it anymore. 
    SELECT pdb_id, pdb_name, status, is_proxy_pdb "IS_PROXY_PDB" FROM dba_pdbs;

    PDB_ID PDB_NAME STATUS  IS_PROXY_PDB
---------- -------- ------- ------------
         3 PDB_ORCL NORMAL  NO
         2 PDB$SEED NORMAL  NO
         6 cdb2     STUB    YES
         7 PDB2     STUB    YES