Oracle Clone Tutorial: How to Clone a Large Oracle Database, Really, Really Fast!

Oracle Clone Tutorial

Take the pain out of cloning! Take the time out of cloning!

Learn how to duplicate (copy) an Oracle database in minutes – no matter how large – with Oracle DNFS.

Do you need to provide read-write clone databases for testing or development? Do you need to do it fast, simply, and with minimal disc space? This free Oracle Database Clone Tutorial will show you how.

Cloning databases can be slow, painful, and requires lots of disc space. Not any more. We can use copy-on-write technology to create as many independent clones as you want, all based on one backup of the source database. Creating a clone takes minutes, no matter how big the database is. The space used by each clone is only the space needed to record changes made within the clone (so initially, zero.) As far as your users are concerned, each clone is an independent database. They will have no idea that they are all sharing a common source.

This facility (based on Oracle’s Direct NFS technology) was introduced in release and formally documented in 12.1.x.

Presented by Oracle Certified Master John Watson, SkillBuilders’ Director of Oracle Database Services.

This free tutorial is segmented into several separate lessons:

  1. Introduction to John Watson, SkillBuilders Director of Oracle Database Services (1:32)
  2. Agenda (1:19)
  3. Clones, Clones and More Clones. Too Many Clones? (6:19)
    John explains the reasons for creating clones and demonstrates DBMS_WM, the Oracle supplied Workspace Manager package, in the hopes of demonstrating a technique for creating *less clones*.
  4. Cloning the Old Way (1:36) (click on video below)
    John explains the three traditional cloning techniques: manual scripting, Data Guard and RMAN.
  5. Cloning Issues and Sample Script (3:41)
    John demonstrates (examples) cloning via a script we wrote to clone databases daily.
  6. Introducing DNFS Copy on Update to Clone (8:16)
    John explains a new technique for cloning : using Direct Network File System (DNFS) Copy-on-Update
  7. DNFS Cloning Technique and Demonstration (19:06)
    John demonstrates (examples) the new technique for cloning : using Direct Network File System (DNFS) Copy-on-Update
  8. Demo Creating Additional Clones ( In 2 Minutes! ) (3:40)
    In 2 minutes and 11 seconds, John demonstrates creating an additional clone – of any size!
  9. Review Technique and Limitations (3:23)

Date: Aug 14, 2013

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Cloning the Old Way

Lightning Fast Cloning


Session 4 – Cloning the Old Way




>> John:  So how do you do it? Right. The traditional way of cloning your database.


Well, I’ll go from the bottom up on this slide. Do it manually. You copy the entire database to a different location, you create a control file for it, you change the name, you change the DBID, you open a resetlog and there you are with the clone database. Fine. But clone databases I always think the whole routine –




I’d never want to do it that way. I’ve seen too many errors. It’s dreadfully prone to error, particularly if the clone is on the same machine as the source. One of our clients about a year ago during their manual cloning routine destroyed their production database. Why? Minor mistake in the script and they overwrote the control file of the production database with the control file of the clone. It’s very prone to error.




Alternative technique – Data Guard. Much better, but you got licensing issues of course. Enterprise Edition, yeah. Particularly if you want to use real application testing it becomes even more expensive, but certainly a good solution provided licensing is not an issue.


Most people will be cloning with RMAN. I certainly would generally be cloning with RMAN. If the RMAN technique is not so prone to error at all, it will make sure you never do accidently overwrite the database but it’s still quite a lot of work to setup.


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