||The thermal stability factor KumVm/kT and the anisotropy constant ratio Ku/Kbulk necessary for 10 years of archiving in heat-assisted magnetic recording of 2 Tbpsi are evaluated by employing a bit error rate calculation using a grain error probability P. Although the attempt frequency f0 in P is a function of the Gilbert damping constant, the Curie temperature, Ku/Kbulk, the grain volume, and temperature, f0 can be treated as a constant for this calculation. The Gilbert damping constant and the Curie temperature variation are parameters with little impact for the information stability. On the other hand, the grain size variation, the grain number per bit n, the mean Curie temperature Tcm, and the storage temperature T are parameters with a strong impact for the information stability. Although KumVm/kT decreases as n increases due to a statistical problem, a larger Ku/Kbulk is necessary as n increases due to a smaller grain size. A larger Ku/Kbulk is also necessary as Tcm decreases. The bit error rate increases rapidly as T increases.