DBUA and Read-Only Tablespaces – Things to Know II

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Thanks to Rodolfo Baselli commenting on a previous blog post about the DBUA and Read-Only Tablespaces I dug a bit deeper and found out that “assuming silently” does not mean “works as intended“.

But one piece after another.

Rodolfo commented that if he triggers the DBUA to switch all data tablespaces into read-only mode for the duration of the upgrade it will be still him to create the correct backup, the DBUA won’t do it.

This is the option in the Oracle Database 12.1.0.2 DBUA (Database Upgrade Assiatant):

DBUA - Tablespaces in Read Only Mode

I did silently assume that the DBUA will choose the correct backup strategy automatically when it offers (enabled by default) to create an Offline Backup on the Recovery Options screen a while later in the same dialogue.

Backup Strategy DBUA

But in fact it doesn’t.

When you choose the default, “Create a New Offline RMAN Backup” it will create a full offline RMAN  backup to the desired location – but not an partial offline backup as intended by the optional trigger to have the tablespaces in read-only mode during upgrade to allow a fast and simple restore without the need for a recovery. Please note that I would recommend this option generally only in cases where the database is on purpose in norarchivelog mode or where the RTO (Recovery Time Objective) is met only by restoring a partial offline backup.

What are your options now?

If you switch on the Read-Only option on purpose you’ll have to choose “I have my own backup and restore strategy” and do the partial offline backup by yourself – before you start the DBUA.

Personally I’d consider this option as not useful when used within the DBUA right now. We have discussed this internally, it may work correctly in a future patch set for the upcoming next release of the database therefore no offense to anybody. It’s just important to know that you’ll have to do the partial offline backup by yourself at the moment.

–Mike

3 thoughts on “DBUA and Read-Only Tablespaces – Things to Know II

  1. "Set user tablespaces read only" creates issue during upgrade.
    It will set ‘users’ tablespace to read only where Java objects are located. So while upgrading JVM we get errors in DBUA. We can ignore and continue the upgrade. But still we require post upgrade actions.

  2. So, if there is an interruption during dbua upgrade to 12c, what is the way to fall back?

    Using flashback? as backup restore will take more time.

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