OSX Hard Drive Clicking
After buying a new Mac Mini, I quickly became aware of a rather annoying clicking sound. Imagine sitting in a quiet room, working silently, then hearing a soft clicking sound. Imagine this sound happening seemingly randomly, at a frequency of about once every 5 minutes. It drove me up the wall.
I did a lot of searching, combing of various forums, and came up with some threads with similar problems. This problem isn’t very well documented or discussed, and I despair to think of the number of hard drives suffering from early demise due to this.
Retail hard drives have their own power management and motion sensors, and Apple doesn’t expect them to. They ship their own drives with these features dialed back, and handle the controls at the OS level. So we have a situation where both the OS and the hard drive are attempting to control the drive’s activity, in particular when it parks its drive heads, and it serves to drive up the load cycles.
I was curious if this problem happened only in my circumstances, so I borrowed 2 laptops from my parents and ran some diagnostics. I was just a bit shocked with the results:
Thinkpad x60s, Toshiba MK6032GSX (stock, 3 years old) 4 Start_Stop_Count 0x0032 100 100 000 Old_age 3607 9 Power_On_Hours 0x0032 094 094 000 Old_age 2513 192 Power-Off_Retract_Count 0x0032 100 100 000 Old_age 51 193 Load_Cycle_Count 0x0032 088 088 000 Old_age 126449 Thinkpad x61t, Hitachi Travelstar 7K100 (stock, 2 years old) 4 Start_Stop_Count 0x0012 099 099 000 Old_age 2467 9 Power_On_Hours 0x0012 079 079 000 Old_age 9625 192 Power-Off_Retract_Count 0x0032 100 100 000 Old_age 1175060616 193 Load_Cycle_Count 0x0012 088 088 000 Old_age 129851 Western Digital Scorpio Black 320 (retail, brand new, installed 29 hours ago) 9 Power_On_Hours 0x0032 100 100 000 Old_age 29 192 Power-Off_Retract_Count 0x0032 200 200 000 Old_age 12 193 Load_Cycle_Count 0x0032 200 200 000 Old_age 1908 Western Digital Raptor 150 (retail, year old application drive) 4 Start_Stop_Count 0x0032 100 100 000 Old_age 197 9 Power_On_Hours 0x0032 084 084 000 Old_age 12126 12 Power_Cycle_Count 0x0032 100 100 000 Old_age 188 Toshiba - Cycles per hour: ~50 Hitachi - 1,174,460,616 cycles over lifetime - Cycles per hour: ~13 - Emergency head parks per hour: 122,084 WD Scorpio - Cycles per hour: ~65
The Toshiba drive seems just fine. Its seen light use, and the hard drive shows it. The Hitachi drive however, concerned me. Its seen 3 times the power on hours of the Toshiba, yet seen 23 million times the number of emergency head parks.
The Mac Mini’s brand new WD Scorpio Black had a very high load cycle count for a drive 29 hours old. If the drive continues to get 1908 cycles per day, at the end of a year it will be at 696,420. Most hard drive have a guaranteed load/unload cycle duty of 600,000. This puts the drive well beyond the advertised number of cycles.
Dealing With It
The novice user should never encounter this problem. They’ll use Apple’s stock hard drives, get replacements and upgrades directly from Apple, and all will be well. If you’re the type of person who upgrades their own internal drive, or buys an external enclosure and a drive for storage, you’re going to have to deal with this.
The solutions I ended up adopting were twofold: For my external drives, I buy Western Digital; they provide tools to alter the drive’s power management settings. For my internal drives, I run hdapm to achieve the same result.