I'm trying to get the percent space used of flash recovery area (FRA) of my databases. I tried to get the percent space used of FRA of one database in OS level using VB script and I get around 3.02MB usage of the allocated 100GB (shown by db_recovery_file_dest) which is less than 1% space used. The script just get the folder size from D:\oracle\product\10.2.0\flash_recovery_area\.
When I did a query from v$recovery_file_dest and v$flash_recovery_area_usage, I am getting 23.79%. The figure in database-level looks inconsistent to the to OS-level figure.
My question is how does Oracle get the percent space used of FRA? Why is OS-level size not consistent with that of database-level?