Can you downgrade your Oracle Restart installation from Oracle 12c back to Oracle 11g?
Actually there’s no real direct downgrade supported for Oracle Restart. But of course there’s a way to do it.
Basically it is:
- Deconfigure Oracle Restart in 12c
- Configure Oracle Restart in 11g
But wait a minute. It is very important to know if you have upgraded your database already. If that is the case then first you MUST downgrade your database(s) as you can’t manage a higher version Oracle Database with a lower version Clusterware.
So first of all, please downgrade your Oracle database(s) first:
- Downgrade your database – if you haven’t changed COMPATIBLE during the upgrade!
At the next stage you’ll need to “downgrade” the Oracle Clusterware resp Grid Infrastructure for Oracle Restart:
Before you attempt this you’ll need to deconfigure the Restart resources – and please be aware that here’s a small difference in commands between Oracle 18.104.22.168 and Oracle 22.214.171.124.
This is from the documentation for Oracle 126.96.36.199:
- Deconfigure Oracle Restart 188.8.131.52:
- Log in as root
# cd /u01/app/184.108.40.206/grid/crs/install # roothas.sh -deconfig -force
- Once this is complete you can now deinstall the Grid Infrastructure with the deinstall tool
- See the documentation
- Then you will need either to reinstall the previous – for instance Oracle 220.127.116.11 – Grid Infrastructure or – if it’s still present on the machine – reconfigure it by running root.sh from the previous Clusterware’s home
- And finally reconfigure the database(s) again with Clusterware
$ srvctl downgrade database -d db-unique-name -o oraclehome -t to_version
In case you’d plan to do this exercise back from Oracle 18.104.22.168 instead then you’ll have different steps to follow to deconfigure Oracle Restart 22.214.171.124:
- Deconfigure Oracle Restart 126.96.36.199
# cd /u01/app/188.8.131.52/grid/crs/install # /u01/app/184.108.40.206/grid/perl/bin/perl /u01/app/220.127.116.11/grid/crs/install/roothas.pl -deconfig
Regarding ASM backwards compatibility please be aware that changing the COMPATIBLE attributes within ASM will get you in trouble – see the Oracle Database Upgrade Guide for further information:
PS: See bug18160024 or the GI install guide, section A11.4 for the Standalone GI downgrade instructions from 18.104.22.168.0.