RMAN no files found to be unknown to the database error

Here’s a weird error message for my collection…

I’ve been working with a customer to setup a RMAN backup on his standby database (backup is going to SBT). After a while, we decided that we couldn’t avoid using the RMAN catalog so we created one.
Now, when using the catalog, we can backup the database from either the primary or standby instances and that will register to a shared catalog so we could restore from either database.


List of Databases
DB Key  DB Name  DB ID            Database Role    Db_unique_name
------- ------- ----------------- ---------------  ------------------
1       ORCL     1415951511       PRIMARY          ORCL
1       ORCL     1415951511       STANDBY          ORCLDG

The thing is, that if we change the DB_UNIQUE_NAME of the backup pieces (using RMAN’s CHANGE command), they will now be “owned” by the wrong database server and the files will not be available when running CROSSCHECK command.


change backup piece db_unique_name
backup piece handle=/data/fast_recovery_area/ORCLDG/backupset/2016_05_01/o1_mf_nnndf_TAG20160501T174121_cld5dkrj_.bkp RECID=15 STAMP=910719681
change backup piece db_unique_name
backup piece handle=/data/fast_recovery_area/ORCLDG/autobackup/2016_05_01/o1_mf_s_910715737_cld5dm03_.bkp RECID=16 STAMP=910719682
Changed 2 objects db_unique_name

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Moving a 3TB Database Datafiles With Only 2 Minute Downtime


In the last week, I had couple of my customer ask me the same question: how can we move our data files between disks with minimum downtime?

This is actually a really good question. When we want to move a database around (let’s say to a new storage or a new disk device) we will need to do it when the files are closed (offline or database down) in order to keep them consistent.  We can do it tablespace by tablespace or the entire database but at the end, it all depends on the size of the files that needs to be transferred. By the way, in Oracle 12c this problem is obsolete since there is an online move command

In the example I’m giving here, the customer had a 3 TB database with most of it in the same tablespace. The downtime allowed by the customer SLA to his customers was around 5-7 minutes so we obviously couldn’t take the database down or take the tablespaces offline. We needed another solution.

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