The reason is again while adding the database to your fail safe group it has to check each and every resoureces of the particular database with the two nodes.

For that it is better to create the database with oracle fail safe itself.only thing you have to do is create the initfile.

rest everything it will take care which is quite easy and less complicated.

Here again the problem is it will rename the old tnsnames.ora to tnsnames.ora.001 or something like that.

Again you can start and shutdown as you do normally.

But it is a good practice to start and shutdown only through oracle fail safe.