Database Software

I was not sure this was the most appropriate forum for this question; if not, please feel free to make an alternative suggestion.

For those of us who run multiple databases on a box with shared disk for FRA, I am finding the extra layer of ASM and db_recovery_file_dest_size to be a minor inconvenience. The Best Practice white papers I have found so far say that you should use db_recovery_file_dest_size, but they do not specify how you should set it. Currently, we have been setting db_recovery_file_dest_size rather small, as the databases so far are small and even at 3x the database size, the parameter is still significantly smaller than the total disk available in that diskgroup.

So, my question; is there any downside to setting db_recovery_file_dest_size equal to the total size of the FRA diskgroup for all databases? Obviously, this means that the amount of free space in the diskgroup may be consumed even if db_recovery_file_dest_size is not yet full (as reflected in the instance V$RECOVERY_FILE_DEST). But is that really a big deal at all? Can we not simply monitor the FRA diskgroup, which we have to do anyway? This eliminates the need to worry about an additional level of disk management. I like to keep things simple.

The question is relevant to folks using other forms of volume management (yes, I know, ASM is "not a volume manager"), but seems germane to the ASM forum because most articles and DBAs that I have talked to are using ASM for FRA.

Most importantly, what ramifications does "over-sizing" db_recovery_file_dest_size have? Aside from the scenario above.

TIA