Can we migrate our database with Oracle Data Guard?
We are getting this question asked quite often during our workshops or via email. And if you are staying within the same operating system family (such as Red Hat 5.8 to OL 7) all is fine, and this is one of the best and most simple approaches to jump between servers. Even when you add a subsequent database upgrade all is very straight forward.
But what if you mix operating systems?
The Support Note for Heterogeneous Data Guard Configurations explains which combinations are allowed beginning with specific releases:
The most popular combinations are Windows to Linux or Intel Solaris to Linux beginning with Oracle 11.1. One combination often requested was IBM AIX to Oracle SPARC Solaris. And we did support this for a few weeks – a white paper got published – and taken away shortly after, removing the support as it turned out that the control file had 5 or 6 pieces which were highly OS dependent. There were rumors circling around you still could do it with a bit of manual extra work.
Now (ok, since end of March 2015), surprise-surprise, there’s an official MOS Note available explaining on how to migrate away from IBM AIX to SPARC Solaris by using a Physical Standby Database beginning with Oracle 18.104.22.168:
But the support has been revoked afterwards as there were some issues. The migration from AIX to SPARC Solaris works officially in a supported way from Oracle Database 22.214.171.124, but may be doable with the below workaround to recreate controlfiles with Oracle Database 126.96.36.199 as well.
The key action is to recreate the controlfile. To recreate a new primary control file, use the following procedure:
- On the open production, connect as SYSDBA, and issue “alter database backup controlfile to trace;”
- In the trace file for this session you will see two sets of DDLs to create a new backup control file. Use the set of DDLs that create the control file with the NORESETLOGS option (Set # 1)
- Shutdown the production database
- Run the commands in the trace file starting with ‘startup NOMOUNT’, ‘CREATE CONTROLFILE REUSE .. NORESETLOGS ..’, ‘RECOVER DATABASE’, etc..
And how about Big to Little Endian platforms?
As the redo stream is highly OS dependent I don’t think that we’ll see combinations such as HP-UX to OL in the near future – just my feeling. But with the offering of Full Transportable Export/Import and the help of RMAN Incremental Backups (see this presentation in our Slides Download Center about it: ) we have very strong alternative in place.