The invention provides a system control method, a device, a computer and a computer-readable storage medium, which relate to the computer field based on cloud storage. The system control method of theinvention is applied to a server system. The method comprises the following steps: the storage information of a target server cluster is analyzed by using a preset evaluation model to obtain predicted capacity expansion data of the target server cluster, wherein the predicted capacity expansion data at least comprises predicted capacity expansion time; If the system time of the server system is within the preset range of the estimated capacity expansion time, the capacity expansion prompt is output according to the estimated capacity expansion data. The invention is favorable for the management and control personnel to expand the capacity of the server system.