A method of controlling repair of a volatile memory device, the method comprising: performing a patrol read operation (PROPRi) to identify error position information of one or more errors included in read data from a memory block (MB0 - MBk) of the volatile memory device, wherein the error position information comprises address information on position within the memory block (MB0, MBk); obtaining accumulated error information by accumulating the error position information based on the patrol read operation (PROPRi), wherein the accumulated error information comprises at least one correctable error number corresponding to a respective candidate fail row address (PFRADD); identifying error attribute information based on the accumulated error information the error attribute information indicating correlation between the one or more errors included in the read data and lines of a line structure of the block of the volatile memory device, the lines comprising at least one main line and sub lines (SWL1 - SWL4) of a said main line; and if the correctable error number corresponding to each said candidate fail row address (PFRADD) is equal to or greater than a reference error number, performing a runtime repair operation with respect to the memory block (MB0, MBk) of the volatile memory device based on the accumulated error information and the error attribute information wherein the runtime repair operation replaces an address where a said error occurred with a repair address, and otherwise repeating the performing the patrol read operation (PROPRi) and the obtaining accumulated error information to update the accumulated error information and the error attribute information performing a patrol read operation (PROPRi) to identify error position information of one or more errors included in read data from a memory block (MB0 - MBk) of the volatile memory device, wherein the error position information comprises address information on position within the memory block (MB0, MBk); obtaining accumulated error information by accumulating the error position information based on the patrol read operation (PROPRi), wherein the accumulated error information comprises at least one correctable error number corresponding to a respective candidate fail row address (PFRADD); identifying error attribute information based on the accumulated error information the error attribute information indicating correlation between the one or more errors included in the read data and lines of a line structure of the block of the volatile memory device, the lines comprising at least one main line and sub lines (SWL1 - SWL4) of a said main line; and if the correctable error number corresponding to each said candidate fail row address (PFRADD) is equal to or greater than a reference error number, performing a runtime repair operation with respect to the memory block (MB0, MBk) of the volatile memory device based on the accumulated error information and the error attribute information wherein the runtime repair operation replaces an address where a said error occurred with a repair address, and otherwise repeating the performing the patrol read operation (PROPRi) and the obtaining accumulated error information to update the accumulated error information and the error attribute information