Hi Andreev,
> Guides recommend to install rdbms and grid under user oracle. I'm in doubt what to do with existing rdbms installation under user ora<sid>.
Yes - you need to install all the components with the user "oracle", but this does not harm your current running system in any case. As you want to migrate to ASM - you will use "shared" resources like the ASM instance and so you usually also use a shared oracle software installation for all the database instances.
From the documentation you already referred to:
- <IHRDBMS> = If you are running multiple databases from the same Oracle Home install the software to '/oracle/RDBMS/11202'.
- <OHGRID> = ‘/oracle/GRID/11202’, ‘/oracle/GRID/11203’, ...
As you can see there is no conflict at all and you just have to set the symbolic link to the "new" <IHRDBMS> later on. "chown" is not recommended and not needed in case of a shared environment.
Regards
Stefan