According to an example, to allocate disk storage space, a request to store a new data chunk in a container is received. For a list of available containers, an exposure count for the container is fetched in the event that a container comprises a data chunk from a same source as the new data chunk. An optimal container to store the new data chunk is determined, and in the event that an exposure count of the optimal container is less than an exposure count limit, the new data chunk in the optimal container is stored.