Refreshing PDB from Primary

1 1. Introduction
2 2. DDC Parameters
3 3. Example
4 4. Refresh using refresh_pdb procedure

1. Introduction

One of the key features in Dbvisit Standby Version 10.0.x is the support of refresh of a pluggable database to standby. Oracle has announced the support of up to three pluggable databases in Standard Edition 2 from 19c. With Dbvisit Standby 10.0.x, any new pluggable databases added to primary is automatically refreshed in the standby database when you send archivelogs from primary and apply them in standby without having to re-create the standby database.

Adding a snapshot pluggable database to primary is not supported for this process.

2. DDC Parameters

There are two new parameters which need to be set to appropriate values before creating the pluggable database or before sending archivelogs from primary to standby after adding the pluggable database. The parameters are

BCKDIR

BCKDIR_DR

The above parameters by default have the value of $DBVISIT_BASE\standby\backup\{DDC} directory.

BCKDIR parameters hold the backup of the pluggable database that was recently added in the primary and its recommended to provide a proper location unless the pluggable database is added from the seed database. The backups taken are by default compressed RMAN backup, and we recommend providing a location with enough free space if the pluggable database is refreshed from an existing pluggable database or it is attached from a different server.

BCKDIR_DR parameter is the location in the standby server where the backup of the pluggable database is transferred from the primary. This location too must have enough free space to accommodate the backup of the pluggable database.

3. Example

3.1 Environment Details

Primary Server: Kiwi701

Database: DEV

Database Instance in ASM

ASM Instance : +ASM

Standby Server: Kiwi702

Database: DEV

Database Instance in ASM

ASM Instance : +ASM

For this example, the default location of BCKDIR and BCKDIR_DR parameter is used

[oracle@kiwi701 /usr/dbvisit/standby]$ ./dbvctl -d DEV -f print_var -a name=BCKDIR
/usr/dbvisit/standby/backup
[oracle@kiwi701 /usr/dbvisit/standby]$ ./dbvctl -d DEV -f print_var -a name=BCKDIR_DR
/usr/dbvisit/standby/backup

3.2 Add pluggable database in the primary

Now, let's add a pluggable database in the primary from seed database.

SQL> sho pdbs

    CON_ID CON_NAME			  OPEN MODE  RESTRICTED
---------- ------------------------------ ---------- ----------
	 2 PDB$SEED			  READ ONLY  NO
	 3 DEVPDB			  READ WRITE NO
SQL> select host_name from v$instance;

HOST_NAME
----------------------------------------------------------------
kiwi701.oraclekiwi.co.nz

SQL> create pluggable database DEVPDB2 admin user DEVPDB2 identified by devpdb2 ;

Pluggable database created.

SQL> sho pdbs

    CON_ID CON_NAME			  OPEN MODE  RESTRICTED
---------- ------------------------------ ---------- ----------
	 2 PDB$SEED			  READ ONLY  NO
	 3 DEVPDB			  READ WRITE NO
	 4 DEVPDB2			  MOUNTED
SQL> alter pluggable database DEVPDB2 open;

Pluggable database altered.

SQL> alter pluggable database all save state;

Pluggable database altered.

SQL> sho pdbs

    CON_ID CON_NAME			  OPEN MODE  RESTRICTED
---------- ------------------------------ ---------- ----------
	 2 PDB$SEED			  READ ONLY  NO
	 3 DEVPDB			  READ WRITE NO
	 4 DEVPDB2			  READ WRITE NO
SQL> select name,guid from v$pdbs;
NAME			       GUID
------------------------------ --------------------------------
PDB$SEED		       87C9DB3334B2180EE053AB02000A067B
DEVPDB			       87CA561EA0712598E053AB02000AF73A
DEVPDB2 		       B70775868225222CE053AB02000AB1E0
SQL> alter session set container=DEVPDB2;

Session altered.
SQL> select name from v$datafile;

NAME
--------------------------------------------------------------------------------
+DATA/DEV/B70775868225222CE053AB02000AB1E0/DATAFILE/system.628.1059847255
+DATA/DEV/B70775868225222CE053AB02000AB1E0/DATAFILE/sysaux.623.1059847257
+DATA/DEV/B70775868225222CE053AB02000AB1E0/DATAFILE/undotbs1.548.1059847255

SQL> create tablespace users;

Tablespace created.

SQL> alter tablespace users add datafile;

Tablespace altered.

SQL> select name from v$datafile;

NAME
--------------------------------------------------------------------------------
+DATA/DEV/B70775868225222CE053AB02000AB1E0/DATAFILE/system.628.1059847255
+DATA/DEV/B70775868225222CE053AB02000AB1E0/DATAFILE/sysaux.623.1059847257
+DATA/DEV/B70775868225222CE053AB02000AB1E0/DATAFILE/undotbs1.548.1059847255
+DATA/DEV/B70775868225222CE053AB02000AB1E0/DATAFILE/users.632.1059847503
+DATA/DEV/B70775868225222CE053AB02000AB1E0/DATAFILE/users.631.1059847527

3.3 Send archivelogs using CLI

The next step is to send archivelogs from primary, this step will take the backup of the pluggable database DEVPDB2. The backup is taken in the default location of BCKDIR (/usr/dbvisit/standby/backup/{DDC}) and the backup files are sent to standby. This is done by running just the dbvctl command to send archivelogs to standby.

This step does not have to be done manually if your daemon service is running this step would automatically be taken care during the next scheduled send of archivelogs to standby. But, if your pluggable database is not created from seed database, we recommend stopping the daemon service and run the below command manually.

[oracle@kiwi701 /usr/dbvisit/standby]$ ./dbvctl -d DEV
=============================================================
Dbvisit Standby Database Technology (10.0.0RCFINAL_0_g6d0007e9) (pid 9606)
dbvctl started on kiwi701: Tue Dec 22 18:15:46 2020
=============================================================

>>> Obtaining information from standby database (RUN_INSPECT=Y)... done
    Thread: 1 Archive log gap: 1. Transfer log gap: 0

Note FORCE_LOGGING is disabled in the primary database.

>>> Exporting PDB B70775868225222CE053AB02000AB1E0... done
>>> Transferring Log file(s) from DEV on kiwi701 to kiwi702:

    thread 1 sequence 249 (thread_1_seq_249.380.1059848245)... done
    thread 1 sequence 250 (thread_1_seq_250.580.1059848245)... done
    thread 1 sequence 251 (thread_1_seq_251.629.1059848247)... done

=============================================================
dbvctl ended on kiwi701: Tue Dec 22 18:17:47 2020
=============================================================

The backup files are automatically removed as soon as the files are transferred to the standby server.

3.4 Apply archivelogs using CLI

The next step is to run the default apply archivelogs command in the standby. This command would restore the PDB backup that was taken earlier and also recover the database.

After the pluggable database is refreshed the backup created under the $DBVISIT_BASE/standby/backup/DEV is automatically deleted.

4. Refresh using refresh_pdb procedure

The pluggable database that is created in the primary can be refreshed using the procedure refresh_pdb as well in the standby. In below example, we see how this is done.

Find the GUID of the pluggable database

Run the PDB refresh command