A storage system, wherein the storage system comprises a controller and a solid state disk , the controller is capable of communicating with the solid state disk , the solid state disk comprises multiple channels, and each of the multiple channels is connected to multiple dies, wherein the controller is configured to: create multiple segments; select a first die from the multiple dies; select a first segment from the multiple segments, and determine an available offset of the first segment; generate a write request, wherein the write request comprises a write address, target data, and a data length of the target data, and the write address comprises an identifier of a channel connected to the first die, an identifier of the first die, an identifier of the first segment, and the available offset; and send the write request to the solid state disk ; the solid state disk is configured to receive the write request, and store the target data according to the write address and the data length of the target data; and wherein the controller is further configured to record an amount of valid data stored in each of the multiple dies; and the controller is specifically configured to select a die in which an amount of valid data is less than a second threshold as the first die; wherein selecting the first die based on the second threshold comprises - valid data amount balancing principle, wherein if there are multiple dies in which the amounts of valid data are less than the second threshold, the controller has a processing manner: selecting a die in which an amount of valid data is smallest as the first die. the controller is configured to: create multiple segments; select a first die from the multiple dies; select a first segment from the multiple segments, and determine an available offset of the first segment; generate a write request, wherein the write request comprises a write address, target data, and a data length of the target data, and the write address comprises an identifier of a channel connected to the first die, an identifier of the first die, an identifier of the first segment, and the available offset; and send the write request to the solid state disk ; the solid state disk is configured to receive the write request, and store the target data according to the write address and the data length of the target data; and wherein the controller is further configured to record an amount of valid data stored in each of the multiple dies; and the controller is specifically configured to select a die in which an amount of valid data is less than a second threshold as the first die; wherein selecting the first die based on the second threshold comprises - valid data amount balancing principle, wherein if there are multiple dies in which the amounts of valid data are less than the second threshold, the controller has a processing manner: selecting a die in which an amount of valid data is smallest as the first die. - valid data amount balancing principle, wherein if there are multiple dies in which the amounts of valid data are less than the second threshold, the controller has a processing manner: selecting a die in which an amount of valid data is smallest as the first die. <EOS>