1. Introduction
Oracle Multitenant
architecture provides a flexible and efficient way to
manage databases using Container Databases (CDB) and Pluggable
Databases (PDB). One of its key advantages is the ability to rapidly
provision and clone databases for development, testing, reporting,
backup validation, and migration activities.
A Pluggable Database
(PDB) clone is a copy of an existing PDB created within the same CDB or another
CDB. Oracle 19c supports multiple cloning methods based on business
requirements, downtime tolerance, and infrastructure design.
In real-world enterprise environments, DBAs commonly receive requests such as:
- Create DEV environment from
Production
- Refresh UAT with latest PROD data
- Provision PREPROD for application
testing
- Create isolated environments for
patch validation
Instead of manually
creating databases and importing data, Oracle PDB cloning enables fast and
efficient environment provisioning while maintaining Oracle Multitenant
architecture standards.
In this implementation
activity, the following Oracle 19c PDB cloning approaches were successfully
performed and validated in a Linux x86_64 environment:
- Approach 1
– Relocate / Hot Clone (Oracle 19c+)
- Approach 2
– Local Clone from Existing PDB
- Approach 3
– Clone from PDB$SEED (Fresh Empty PDB)
These cloning methods
help reduce deployment time, simplify database provisioning, support rapid
environment duplication, and improve operational flexibility for DBAs and
application teams.
This document provides a
practical step-by-step implementation guide for Oracle 19c PDB cloning methods,
including provisioning, cloning operations, validation, and post-clone
verification in a production-like environment.
2. Objective / Scope
Objective
• Understand Oracle 19c
PDB cloning methods
• Create new PDBs using different cloning approaches
• Validate successful clone operations
• Preserve application schemas and data during cloning
• Demonstrate Oracle Multitenant provisioning capabilities
Scope
• Oracle Database 19c
Environment
• Oracle Multitenant Architecture
• PDB Cloning Operations
• Single Instance Environment
• Non-RAC Setup
• File system-based database
• Local cloning and hot cloning methods
• Includes clone validation and post-check verification
3. Environment Details
|
Component |
Value |
|
Oracle Version |
19.3.0.0.0 |
|
OS |
Linux x86_64 |
|
CDB Name |
PRODCDB |
|
Source PDB |
PROD |
|
Storage Type |
Filesystem |
|
Architecture |
Multitenant (CDB/PDB) |
|
Cloning Methods |
Seed Clone, Local Clone, Hot Clone |
4. Prerequisites
• Source PDB should be
healthy and accessible
• Ensure enough filesystem storage is available
• Verify target file locations and permissions
• Enable ARCHIVELOG mode for hot clone operations if required
• Ensure local undo mode is enabled for hot cloning
• Take backup before cloning activity
• Verify no file name conflicts exist
• Validate listener and service connectivity
5. Implementation
Verify Existing CDB and
PDB Environment
Before cloning
operations, verify the CDB and existing PDB details.
Purpose:
• Validate source environment
• Confirm PDB availability
• Verify database open mode and health
Validation includes:
• CDB status
• PDB status
• Database version
• Application schemas and tables
This ensures the
environment is ready for cloning activities.
Approach 1 –
Relocate / Hot Clone (Oracle 19c+)
This
method allows a PDB to be cloned or relocated while the source PDB remains
online and accessible to users. Oracle 19c introduced Hot Clone capability to
minimize downtime during migration or cloning activities.
It
is commonly used for workload migration, environment refresh, database
consolidation, and moving PDBs between CDBs with minimal service interruption.
Purpose:
• Reduce downtime during cloning
• Clone active databases
• Improve operational flexibility
Requirements:
• ARCHIVELOG mode enabled
• Local undo enabled
• Source PDB in READ WRITE mode
Enable ARCHIVELOG Mode
Hot
cloning in Oracle 19c requires the source database to run in ARCHIVELOG mode.
This allows Oracle to maintain transactional consistency while cloning the PDB
online without downtime.
Database was restarted in
MOUNT mode and ARCHIVELOG was enabled.
Commands used:
Verification:
PDB status was also
verified:
This step ensures the
source environment is ready for online cloning operations.
Verify Hot Clone
Prerequisites
Oracle
19c Hot Clone requires LOCAL UNDO mode to be enabled in the Container Database
(CDB).
Validation performed:
If the value is FALSE,
LOCAL UNDO must be enabled before proceeding with Hot Clone operations.
Purpose of this step:
- Validate
Oracle 19c Hot Clone requirements
- Ensure
online cloning support
- Prevent
clone operation failure
Prepare Target Directory
for Clone PDB
A new operating system
directory was created for the target UAT PDB datafiles.
Commands used:
Verification:
Purpose:
- Store
cloned PDB datafiles
- Maintain
separate filesystem structure
- Avoid
file conflicts with source PDB
Source PDB PROD was also
verified in READ WRITE mode because Hot Clone requires the source PDB to remain
online during cloning.
Verification:
Perform Hot Clone
Operation
The
UAT PDB was cloned online from the existing PROD PDB using the CREATE PLUGGABLE
DATABASE statement.
Command used:
Explanation:
- FROM
PROD → Source PDB for cloning
- FILE_NAME_CONVERT
→ Changes source file paths to target clone location
Verification:
Output confirmed:
- Source
PDB PROD remained online
- Target
PDB UAT was created successfully in MOUNTED state
Datafiles were also
validated:
This
step successfully completed the online PDB clone operation without shutting
down the source PDB.
Open and Configure Cloned
PDB
After cloning, the newly
created UAT PDB was opened in READ WRITE mode.
Command used:
Verification:
PDB state was saved for
automatic startup after database restart:
Purpose of this step:
- Activate
cloned PDB
- Validate
clone health
- Ensure
persistent open state after restart
Verify
Cloned PDB Datafiles
Final
validation was performed to confirm that all cloned datafiles were created
successfully under the target UAT directory.
Command used:
Verification confirmed:
- SYSTEM
tablespace datafile
- SYSAUX
tablespace datafile
- UNDO
tablespace datafile
- USER
datafiles
This
step confirms successful Oracle 19c Hot Clone implementation and proper
datafile mapping for the cloned UAT PDB.
Approach
2 – Local Clone from Existing PDB
This
method creates a duplicate copy of an existing PDB inside the same Container
Database (CDB). It is mainly used when an exact copy of a database is required
for DEV, UAT, reporting, testing, or troubleshooting purposes.
The
cloned PDB includes application schemas, objects, and data, making it useful
for quickly provisioning environments without manual export/import activities.
Verify Existing PDB
Environment
First, the existing PDB
environment was verified to confirm the source PDB status before starting the
clone operation.
Verification:
Output confirmed:
- PROD
PDB available as source database
- UAT
PDB already operational
- Source
PDB PROD running in READ WRITE mode
This step ensures the
source environment is ready for local cloning activity.
Open Source PDB in READ
ONLY Mode
For
local cloning operations, the source PDB was opened in READ ONLY mode to
maintain consistency during the clone process.
Commands used:
Verification:
Purpose of this step:
- Maintain
consistent clone copy
- Prevent
data modifications during cloning
- Prepare
source PDB for local clone operation
Output confirmed:
- PROD
opened successfully in READ ONLY mode
Prepare Target Directory
for PREPROD PDB
A new operating system
directory was created for the PREPROD PDB datafiles.
Command used:
Purpose:
- Store
cloned PREPROD datafiles
- Maintain
separate filesystem structure
- Avoid
conflicts with source PDB datafiles
This step prepares the
target location for cloned database files.
Create PREPROD PDB Using
Local Clone
The
PREPROD PDB was created by cloning the existing PROD PDB within the same
Container Database (CDB).
Command used:
Explanation:
- FROM
PROD → Source PDB for cloning
- FILE_NAME_CONVERT
→ Maps source file paths to target PREPROD location
Verification:
Output confirmed:
- PREPROD
PDB created successfully
- Initial
status showed as MOUNTED
This step completed the
local PDB cloning operation successfully.
Open and Configure
PREPROD PDB
After successful cloning,
the PREPROD PDB was opened in READ WRITE mode.
Command used:
Output confirmed:
- PREPROD
opened successfully in READ WRITE mode
Purpose:
- Activate
cloned PDB
- Make
database available for application access
- Validate
successful clone operation
Reopen Source PROD PDB in
READ WRITE Mode
After clone completion,
the source PROD PDB was reopened in READ WRITE mode for normal operations.
Commands used:
Output confirmed:
- PROD
returned to READ WRITE mode
- PREPROD
and UAT remained operational
PDB states were saved:
This step restores the
production PDB to normal operational mode.
Verify PREPROD Datafiles
Final
validation was performed to confirm successful creation of PREPROD datafiles in
the target filesystem location.
Command used:
Verification confirmed:
- SYSTEM
tablespace datafile
- SYSAUX
tablespace datafile
- UNDO
tablespace datafile
- USER
datafiles
This
step confirms successful Oracle 19c Local Clone implementation and proper
filesystem mapping for PREPROD PDB.
Approach 3 – Clone
from PDB$SEED (Fresh Empty PDB)
This
method creates a brand-new empty Pluggable Database using the default Oracle
template database called PDB$SEED. It is commonly used when a fresh environment
is required for new applications, development, or testing activities without
copying existing application data.
This
approach is simple, fast, and widely used for standard PDB provisioning in
Oracle Multitenant architecture.
Verify Existing PDB
Environment
First, verify the
existing CDB and available PDBs before creating the new DEV PDB.
Command used:
- PROD,
UAT, and PREPROD PDBs were available
- PDB$SEED
was in READ ONLY mode
- CDB
environment was healthy and operational
Create OS Directory for
DEV PDB
A dedicated filesystem
directory was created to store DEV PDB datafiles.
Commands used:
- Create
separate storage location for DEV PDB
- Organize
datafiles properly
- Maintain
clean multitenant structure
Verification confirmed
the directory was created successfully.
Create DEV PDB from
PDB$SEED
An attempt was initially
made without specifying an ADMIN USER, which resulted in an ORA-00922 syntax
error.
Observation:
- Fresh
PDB creation from PDB$SEED requires an ADMIN USER because no application
users exist inside the seed database.
Correct command used:
Purpose of this step:
- Create
fresh empty DEV PDB
- Generate
new datafiles from PDB$SEED
- Create
initial administrative user
Explanation:
- ADMIN
USER creates local PDB administrator
- FILE_NAME_CONVERT
maps seed datafiles to DEV location
- PDB
is initially created in MOUNTED mode
Verification:
Output confirmed:
- DEV
PDB created successfully
- Initial
status showed as MOUNTED
Open DEV PDB and Verify
The newly created DEV PDB
was opened in READ WRITE mode.
Command used:
Output confirmed:
- DEV
PDB opened successfully
- Status
changed to READ WRITE
Validate Datafiles and
Save State
Datafiles for DEV PDB
were verified to confirm proper file creation.
Command used:
Verification confirmed:
- DEV
datafiles were created successfully
- Files
existed under /u02/oradata/PRODCDB/DEV/
Finally, PDB state was
saved.
Command used:
Purpose:
- Automatically
open DEV PDB after database restart
- Preserve
current open state
Final validation
confirmed:
- DEV
PDB operational successfully
- Fresh
empty PDB provisioning completed successfully
6.
Risks and Mitigation
⚠ Risks
• Insufficient storage during clone operation
• File path conflicts
• Clone failure due to open mode restrictions
• Service registration issues
• Application connectivity failures
• Performance impact during large clone operations
✅
Mitigation
•
Verify free storage before cloning
• Validate file locations carefully
• Take backup before implementation
• Perform testing in UAT first
• Validate listener and services
• Monitor alert logs during clone operation
• Validate cloned application data post clone
7. Key
Observations
• Oracle 19c Multitenant architecture
supports multiple PDB cloning methods
• PDB$SEED cloning creates fresh empty PDBs quickly
• Local cloning preserved application schemas and data successfully
• Hot clone operation allowed source PDB to remain online
• File system-based cloning completed successfully
• All cloned PDBs opened successfully in READ WRITE mode
• Application connectivity validation completed successfully
• Data consistency verified successfully after cloning
• Clone operations significantly reduced provisioning effort
8. Benefits
• Rapid database provisioning
• Simplified environment creation
• Faster development and testing setup
• Reduced manual administration effort
• Supports Oracle Multitenant architecture
• Enables efficient database consolidation
• Preserves application schemas and data
• Supports modern Dev/Test workflows
• Improves operational flexibility
• Enables faster database deployment strategies
9.
Conclusion
Oracle 19c PDB cloning activities were
successfully completed using multiple multitenant cloning approaches in a
production-like environment.
The implementation included:
- DEV PDB creation using the PDB$SEED approach
- PREPROD PDB creation using Local Clone from existing PROD PDB
- UAT PDB creation using Oracle 19c Hot Clone functionality
The activity validated:
- Successful multitenant provisioning
- Online and offline cloning capabilities
- Proper datafile creation and mapping
- Successful preservation of application schemas and data
- Post-clone validation and application accessibility
All PDB clone operations completed
successfully with proper verification, filesystem validation, and Oracle
Multitenant architecture compliance.
⚠ Caution
/ Disclaimer
The information provided in this document is
for educational and learning purposes only.
Although the procedures were tested
successfully in a controlled environment, always perform proper validation and
testing in UAT or non-production environments before implementing in production
systems.
Ensure proper backups, rollback planning, and
storage validation before performing any cloning activity.
Thank You