Migration query - Oracle I have two physical servers, hosting 6 two node RAC databases running in 11.2.0.3 version (both grid and database).

I'm told to have the grid software in 11.2.0.4 version and the databases in the same 11.2.0.3 version since there could be future plans to upgrade the database to a higher version.

Plan is to create new grid software (11.2.0.4) and create a new ASM instance with new luns and create diskgroups with the new luns, create a new database and then export/import from old database to this new database. So that the new database will have the Grid and ASM running in 11.2.0.4 and database in same 11.2.0.3.

Perform the same activity for all 6 databases, post that uninstall 11.2.0.3 software and binaries, resulting in the required result wherein only one ASM instance will be running (11.2.0.4).

Is the above mentioned activity feasible? I'm not in a situation to upgrade 11.2.0.3 grid to higher version as I cannot afford downtime. But then the above mentioned activity will have two ASM instances running at the same time for some period.

I can add/clear doubts if the mentioned activity is unclear.
I'm sure that such approach is feasible. Technically Grid 11.2.0.4 is fully compatible with RDBMS 11.2.0.3. You just need to be accurate in some parameters.
I believe that in a new 11.2.0.4 grid you won't use very specific "compatible.rdbms" or "compatible.asm" attributes' value ('11.2.0.4.0', e.g.) which might conflict with 11.2.0.3 database. Ideally you should use the same default '11.2.0.0.0' value in target GI.

You can clone databases from old to new GI, copy specific tablespaces if your schemas are compatible with transport_tablespaces approach. You can use logical dump created with datapump.
It might be very useful to use dbms_file_transfer package to copy datafiles (and dumpfiles created by datapump as well) directly from source ASM to target ASM diskgroups.

Good luck.