I just upgraded the HDD of my macbook pro 13", from a stock Hitachi 160G 5400RPM to a Hitachi 500GB 7200RPM, the HDD is fine, quiet(although a little bit noisier than previous one), cool and fast. As the previous HDD suffers from fast-increasing Load_Cycle_Count, I checked the new one using smartmontools(installed via MacPort), unsurprisingly it has the same problem. Here is what Load Cycle Count means from Wikipedia: Count of load/unload cycles into head landing zone position. The typical lifetime rating for laptop (2.5-in) hard drives is 300,000 to 600,000 load cycles. Some laptop drives are programmed to unload the heads whenever there has not been any activity for about five seconds. Many Linux installations write to the file system a few times a minute in the background. As a result, there may be 100 or more load cycles per hour, and the load cycle rating may be exceeded in less than a year. Recall that for the previous HDD I used Hitachi's Feature Tool to reset its APM level to 192, and LCC merely increases, but a PC laptop is needed for doing this and I currently do not have a PC laptop, so I cannot do it for the new HDD. Then I searched on the internet and found this thread: http://forums.macrumors.com/showthread.php?t=910582 Which mentions LCC is actually not related to the 600000 times count but start/stop count is, then I found: I found the HDD's webpage from Hitachi: http://www.hitachigst.com/internal-drives/mobile/travelstar/travelstar-7k500 There is a data sheet, that states: Load / Unload cycle 600,000 Then I'm confused, is it the spin-up/spin-down time but use the same attribute name "Load / Unload cycle" which is equivalent to "Start/Stop Cycles" in SMART and SMART uses the same attribute name(LCC) for another attribute? Have you ever worried about your HDD?