http://www.seagate.com/docs/pdf/newsinfo/disc/drive_reliability.pdf
温度とMTBF http://e-words.jp/w/MTBF.html の関係

温度 MTBF
25   232,140
26   220,533
30   181,069
34   150,891
38   125,356
42   104,463
46    88,123
50    74,284
54    62,678
58    53,392
62    46,428
66    39,464
70    32,500