--> This sound as a good option , BUT :
3. Do as option #2, but instead of leaving the unused space empty, create a completely separate ASM diskgroup whose performance characteristics are independent from the data volumes, and put a DBFS instance on top of it. This is the approach Oracle chose for new Exadata builds.
Actualy , i think its about 10% and not 5% , and basically i am losing 600 GB when only 1 (one) GB is needed for golden gate pump files , which seems to me as a huge waist of space in a quarter rac machine
But keep in mind that, this 30G of storage space over 10 disks represents less than 5% of total storage capacity in 600GB high performance disks