Information processing system and control method of information processing system

An information processing system comprises a processor. The processor executes a process that causes the information processing system to perform first writing, when requested to write data, data from which to subtract remainder data obtained by dividing a data size of write target data by a first data size of first processing unit data, the first data size being a size of processing unit data of a reading/writing process in a first storage device, in the write target data requested to be written to the first storage device and second writing the remainder data not being written by the first writing to a second storage device in which to set a second data size of second processing unit data, the second data size being smaller than the first data size of the first processing unit data.