Thanks for the pointer
but i only use qtree and no quotas for user or group.
My problem is this one
i have to write a policy concerning quotas about the level of overcommitment.
then i have to find a simple way for operator to see the level of overcommitment.
it s like make the sum of quotas of qtrees in a volume in front of the size of volume
but i m wondering if there s a more direct way