Techniques for processing an access request and updating a storage system are provided. For instance, a method comprises: receiving an access request for an object associated with a storage system, the storage system including a plurality of physical nodes, each of the plurality of physical nodes including at least one set of virtual units, each set of virtual units including at least one virtual unit; determining, from a plurality of sets of virtual units included in the plurality of physical nodes of the storage system, a target set of virtual units associated with the object; and determining, from the target set of virtual units, a target virtual unit corresponding to the object. With the technical solution of the present disclosure, not only a set of virtual units on a physical node may be easily split and merged, but also huge computing resources that need to be allocated may be saved, so better user experience may be brought about at a lower cost.