1. A method for space reservation in a deduplication system by a processor, comprising: determining a calculated factoring ratio as a weighted ratio of current nominal data to physical data based on at least one storage capacity threshold and a used storage space currently physically consumed by one of backup and replication data; calculating a maximal nominal estimated space in the computing storage environment; and calculating a remaining space, defined as the maximal nominal estimated space minus a current nominal space in the computing storage environment; wherein if the remaining space is one of equal and less than a user-configured reservation space for backup operations, data replication operations are accepted and stored in the computing storage environment.