A system includes a cluster of nodes including a storage domain, a memory, and a processor. The processor is configured to receive a request to determine an amount of allocated blocks associated with a virtual disk comprising a first volume. Each volume that includes metadata associated with allocated blocks is designated into a first set. Each volume within the one or more layers that lacks metadata associated with allocated blocks and includes an allocation table is designated into a second set. Each volume within the one or more layers that is omitted from the first set and second set is designated into a third set. The amount of allocated blocks within the first volume is determined based on inspecting the metadata of each volume of the first set, inspecting each allocation table of each volume of the second set, and inspecting each block of each volume in the third set.