A method of storing new data in a redundant array of disks is proposed in which said new data are received from a host computer and are stored in a semiconductor memory. An area on at least one disk in said redundant array in which to store said new data is selected and said new data are written on the area thus selected. Said host computer is notified that the storing of said new data is completed as soon as the step of writing the new data ends. Data are read from another area on at least one other disk in said redundant array, computing check information from the new data stored in said semiconductor memory and the data thus read, whereby said check information are written on a disk in said redundant array.