While preparing for the production migration of your Oracle Database using cross-platform transportable tablespaces (XTTS) and incremental backups, you should test the procedure.
It is often impossible to get a full copy of the production database or a comparable test system. If you still want to test the migration procedure, you need to take the backups on the production database. That might have an impact on your production database. You could offload the backups to a standby database but periodically must set tablespaces in read only mode to perform the Data Pump exports. This means downtime for your application.
But there is a way to do all the work on the standby database. This will allow you to test the migration procedure without affecting the primary production database.
You can also read about the procedure in the MOS note Using XTTs in a Data Guard Environment.
You should use the procedure described in a previous blog post about backups on a standby database. When you reach the final incremental backups you need to follow the information below.
I assume you have conducted a level 0 and a number of incremental backups on the standby database. Now it is time for the final incremental backup. We will do this on the standby database as well. You don’t need to touch the primary database except for a few minor changes (archive current log and defer redo log transport).
- Temporarily activate the standby database following the procedure described in MOS note How To Open Physical Standby For Read Write Testing and Flashback (Doc ID 805438.1).
- Connect to the activated standby database, which is now in read write mode, and set the tablespaces read only.
STDBY SQL> alter tablespace ... read only;
- Do the final incremental backup on the standby database using the Perl script:
$ perl xttdriver.pl --restore
- Perform the Data Pump export from the standby database
$ expdp system@stdby transportable=always full=y ...
- Re-instate the activated standby database as a proper standby database following the procedure described in MOS note How To Open Physical Standby For Read Write Testing and Flashback (Doc ID 805438.1).
Now you have a consistent backup of the data files and a corresponding Data Pump export; both components were taken from a standby database. Transfer the files to your target database and test the procedure.
The heading says you can use this procedure for testing. How about the production migration?
Well, it could work, but I would not recommend it.
When you use this approach, you leave the primary database open for business. At the same time, you take the final incremental backup. This opens for a potential catastrophe. Users entering data into the open, primary database while you have taken the last incremental backup. That would mean data loss!
Using the other standby database approach, you are sure that no more data is entered into the source database, when you perform the final migration. You ensure this by setting the tablespaces read only in the primary database. This is why I do not recommend that you use the approach with an activated standby database for your production migration.
You should test your migration procedure and get comfortable with your runbook. You can use a temporarily activated standby database if you don’t have a dedicated test environment. This allows you to perform realistic testing without interrupting the primary database and your users.
Other Blog Posts in This Series
- Full Transportable Export/Import
- What Is a Self-contained Transportable Tablespace Set
- How to Migrate a Database Using Full Transportable Export/Import and Incremental Backups
- Make It Fast
- Backup on Standby Database
- Slow Network Between Source and Target
- Bigfile Tablespaces
- Testing the Procedure On Activated Standby Database
- Target Database and Data Guard
- ASM Aliases and Why You Should Get Rid of Them
- Pro Tips