Allocation exceed Capacity ,but Available  is  not 0.
 
#virsh pool-info 2361a6d4-0edc-3534-87ae-e7ee09199921
Name:           2361a6d4-0edc-3534-87ae-e7ee09199921
UUID:           2361a6d4-0edc-3534-87ae-e7ee09199921
State:          running
Persistent:     yes
Autostart:      no
Capacity:       285.57 GiB
Allocation:     489.89 GiB
Available:      230.59 GiB