An input output (IO) bandwidth control method, an IO access request processing method, an apparatus, and a system relate to the field of storage technologies, where the IO bandwidth control method, executed by a name node, includes determining an IO bandwidth of each data node in at least one data node and an IO bandwidth of a first tenant, and instructing the at least one data node to allocate the at least one IO bandwidth to the first tenant based on the IO bandwidth of each data node and the IO bandwidth of the first tenant, where the at least one IO bandwidth is in a one-to-one correspondence with the at least one data node, and each IO bandwidth in the at least one IO bandwidth is greater than 0 and is less than or equal to an IO bandwidth of a corresponding data node.