Table of Contents
1. Purpose of the document 3
2. Document Usage 3
3. Overview of the Procedure 3
3.1 Introduction 3
3.2 Environments 4
3.3 Assumption 4
3.4 Cloning Process 4
3.4.1 Steps to be followed in Primary database: 4
3.4.2 Steps to be followed in the Secondary database server: 5
5. Conclusion 7
1. Purpose of the document
This document illustrates a process to clone an Oracle database using hot backup. The following sections are covered in this document
Overview
Environments
Assumptions
Cloning process
2. Document Usage
This document can be useful for any Oracle DBA for cloning an Oracle database. Generally cloning databases with the help of source database hot backup is a standard process to effectively and efficiently create a replica of the source database. The process illustrated in this document can be used by any DBA who wants to create a replica of an Oracle database with the help of hot backup and the associated archive logs.
3. Overview of the Procedure
3.1 Introduction
Cloning database is one of the routine DBA activities. Any DBA who administers various environments and is supporting the application development team for database activities has to periodically synchronize the acceptance/testing/development with the Production data.
This frequency of synchronization depends upon the business and application development teams requirements. Generally this process can be done with the below mentioned procedures
1) EXPORT/IMPORT utilities
2) DATA PUMP
3) Cold Backup Restoration
4) Hot Backup Recovery
Each of the above mentioned process has got its own pros and cons. To state a few vital reasons why Hot backup recovery process is chosen widely
a) You can recover to the most recent time period.
b) Doesn’t require outage of the source database
c) Requires less time compared to the other process
d) Best method for large databases
3.2 Environments
1. Primary or the Source database system
2. Secondary or the Target database system
3.3 Assumption
Primary database operated in ARCHIVELOG mode.
Secondary database to be created by cloning in a different server
Primary and Secondary environment Operating system are same.
3.4 Cloning Process
3.4.1 Steps to be followed in Primary database:
1) Perform HOTBACKUP of all the data files
2) LSN number
Login as sys as sysdba
Sql> Alter system archive log current;
Sql> Archive log list
Note down the Current Log Sequence
3) Control file trace
In Sql> prompt issue the statement
ALTER DATABASE BACKUP CONTROLFILE TO TRACE;
You can find the trace file in the udump directory.
3.4.2 Steps to be followed in the Secondary database server:
1) If the secondary database is to be created in a different server
FTP the following to a temporary location in the secondary database server.
a) hot backup of all the primary database data files
b) all the archive log files generated in the primary database after you start hot backup
c) control file trace of primary database
d) pfile of the primary database
2) Edit the pfile as it would be for secondary database server locations
a) Control_files- new locations
b) instance_name – new name
c) background_dump_dest – new location
d) core_dump_dest- new location
e) user_dump_dest – new location
f) log_archive_dest- new location
Save the pfile as init_
$ORACLE_HOME/dbs directory if UNIX
$ORACLE_HOME\database if WINDOWS
Where SID is the instance name given above in the edited pfile
3) In the control file trace Use the “SET #2. RESTLOGS case” CREATE CONTROLFILE section (Since we don’t use the primary database redolog files, we use this option). In that section Copy from “CREATE CONTROLFILE” to “CHARACTER SET
Save the file as cr_control.sql
Edit the following section in cr_control.sql
a) Use SET instead of REUSE
Old: CREATE CONTROLFILE REUSE DATABASE <"PRIMARY_DBNAME" >RESETLOGS
NEW: CREATE CONTROLFILE SET DATABASE <"SECONDARY_DBNAME"> RESETLOGS
b) Edit the LOGFILE paths as per the secondary database environment
c) Edit the DATAFILE paths as per the secondary database environment
d) Save the cr_control.sql file
4) Move the ftp ed Hot backup DATAFILE from temporary location of specific location as specified in the control file cr_control.sql
5) Move the archived logs from temporary location to the location specified in log_archive_dest in pfile
6) If Windows,
Create an oracle service using ORADIM utility
ORADIM -NEW -SID sid | -SRVC service [-INTPWD password] [-MAXUSERS number] [-STARTMODE a|m] [-PFILE file] [-TIMEOUT secs]
In the CMD prompt
SET ORACLE_SID=
Sqlplus “/ as sysdba”
You will get a Connected to an idle instance message.
7) If UNIX,
In the $ prompt give
EXPORT ORACLE_SID=
Sqlplus “/ as sysdba”
You will get a Connected to an idle instance message.
8) In the SQL> Prompt give
STARTUP NOMOUNT
9) Run the cr_control.sql file in the SQL> prompt
If Windows
@
If Unix
@
You should get a message like Control File created
9) Recover the database using backup control file. In the SQL> prompt give
RECOVER DATABASE USING BACKUP CONTROLFILE UNTIL CANCEL;
Note: this can also be done with UNTIL TIME or UNTIL SCN provided you know the time or the SCN until which you want to perform the recovery
10) The recovery process will keep prompting for archive logs. Give return for each prompt of archive log.
Since the required archive logs from Primary database are restored in archive_log_dest of secondary, it will get applied for every return you give in the prompt.
Once the recovery process prompts for the archive log with the LSN number noted in the Primary database, in step 2) of Steps to be done in Primary database section
Give CANCEL in the recovery sql prompt
11) Now you must get a message like
Media recovery cancelled.
12) Now in the SQL prompt give.
ALTER DATABASE OPEN RESETLOGS;
You should get a message like.
Database opened.
12) Bounce the database
SHUTDOWN IMMEDIATE;
STARTUP;
13) Check for errors in bdump.
14) Check log switch.
15) Check redo log archival
16) Compare the users, objects, size with the Primary database
17) Take a complete cold back up and maintain that as generation 0 backup.
You have cloned the database.
5. Conclusion
Hot backup recovery is one of the best methods to clone database because there is no outage or down time required in the primary database and data is replicated in secondary database to the most recent time period.
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