Freespace Provider for ONB needs

Since we are storing our arc files on volumes in our IT-Center, we have special needs for the Freespaceprovider. All volumes are under control of our IT-Department. They are deciding how big a volume is and to which size in Percent, we are allowed to store files on these volumes. All volumes which are full of data will be set read only.
These constraints are not working with the default FreeSpaceProvider. We need to implement a OnbFreeSpaceProvider