Control of the variations of island properties is one of the key challenges in fabricating Bit-Patterned Media for future storage systems. The presence on any variation in the size and position of an island has a detrimental effect on the ability to recover recorded data, particularly in the case of variation in island size. By analyzing error events when island size variations are present we have identified that these are more likely to be single-bit in nature. To understand the origins of these error events we have investigated the size and magnetization state of islands in the vicinity where a single-bit error event is encountered. It is shown that these error events occur due to particular combinations of island size and magnetization state for the three islands investigated. In every case the central island, from which the data bit is recovered in error, is small compared to the nominal island size. These results show that size variations must be controlled in the fabrication process in order to maximize the bit-error-rate performance of the read channel
