1. A method for execution by a dispersed storage processing unit, the method comprises: receiving a request to store data in dispersed storage network (DSN) memory; determining whether the data is to be appended to existing data stored in the DSN memory, wherein the existing data is stored in the DSN memory as a set of encoded data slices and wherein the existing data is encoded using a dispersed storage error coding function to produce the set of encoded data slices; and when the data is to be appended: encoding, using an append dispersed storage error coding function, the data to produce a set of encoded append data slices; generating a set of append commands, wherein an append command of the set of append commands includes an encoded append data slice of the set of encoded append data slices and identity of one of a set of dispersed storage (DS) units of the DSN memory; and outputting at least a write threshold number of the set of append commands to at least a write threshold number of the set of DS units.