Disable log shipping from the Primary
Install PSU 220.127.116.11.8 on Standby
Startup Standby in recovery mode. Do NOT run any update SQL on the standby,
Install PSU 18.104.22.168.8 on Primary
Run update SQL on Primary
Re-enable log shipping
Monitor the redo apply from Primary to Standby. This will also upgrade the Standby.
Will depend upon your setup. I believe you can do that with RAC for example.
Here's Oracle's document for reducing downtime:
We do not have RAC as this software is very expensive?
I will ask Management a downtime window of 1 hr from 12:00AM - 1:00AM . Will this be enough?
Then I will apply the patch. Is there a danger that the database not startup? or the app will bug down due to the patch? How will I revert it back?
> I will ask Management a downtime window of 1 hr from 12:00AM - 1:00AM . Will this be enough?
Will 1 hour be enough? It normally is for me, even for my RAC primary and RAC standby. However, I have one system that takes hours to patch (the CPUs run Java really, really slow).
> Is there a danger that the database not startup? or the app will bug down due to the patch?
I haven't seen any such behaviour in all of the Oracle patches that I have deployed. But there is always a danger a patch will break something. You should thoroughly test the patches in non-production before deploying to production. Failure to test the patch in non-production is a career limiting move, in my opinion. Also, if you apply in non-production, you will have a good idea if your 1 hour downtime is enough.
> How will I revert it back?
Have you read the patch instructions in the accompanying Readme file?