Thursday, March 23, 2017

Hard Drive Load Cycle Count

I finally found and downloaded a Mac SMART utility (DriveDx) that works with compatible external enclosures to check the status on a few external media drives on my Mac Mini server.

To my surprise, a 1TB WD10EARS with 55,395 hours (77 months) had a life-span warning due to load cycle count.  It has 1,228,872 load cycles, and the drives are rated for 300,000!  Wow.

I since obtained a 1TB WD10EVDS to replace the drive.  After research, I grabbed a usb drive with Hirens 15.2, connected to a PC via SATA, and opened the WDIDLE3.EXE utility to confirm the head parking is disabled.  To my surprise, the head parking is disabled from the factory on this WD10EVDS drive.

It took a few minutes to figure out how to launch the utility on Hirens.  I needed to select hard drive tools -> more -> more -> WDIDLE.  After reaching a DOS prompt, cd tools/wdigital/.  Then you can run WDIDLE3 and then follow the flags:

Now that the 1TB WD10EARS has been replaced, I checked the head parking.  It was set to 6 seconds and has been trying to slowly kill itself for the past 7 years.  I disabled it with the /d flag, checked the status again to confirm, and then reconnected to my Mac.  All data is in tact, and no data is lost when changing the idle timer.

Checking other drives:

  • 2TB WD2002FYPS with 13,171 hours (18 months) and 79,413 load cycles.  This is clearly parking.  The timer was set to 12.8 seconds, which equates to 30s.  Now disabled.
  • 2TB WD20EARS with 51,220 hours (71 months) and 322,228 load cycles.  It is clearly parking and is already past the rated 300k cycles so it will be replaced.  Timer set to 8 seconds and now disabled.
  • 1TB WD10EALS - WDIDLE3 timer is set to disabled from the factory.

I also ordered a WD40EFRX to replace the aging WD20EARS.  Once received, I will read the timer setting and confirm it is disabled.


  1. I used this program to check my hard drive because I was having kernel panics. My load cycle count is over 1,000,000 but I found it strange that it said that the drive was still good. Do you know what kind of problems a high load cycle can cause?

  2. Most drives are rated for 300-400k cycle counts -- after that the chances of total drive failure are higher. I also spoke with a coworker who used to work in the HD industry and he said head failures due to excessive parking is one of the leading causes of failure in drives. The resulting failure can be either a head collision with the platter or a head mechanism failure.

    However, as you can see above this 1TB drive was happily spinning along and had over 1.2M cycles.

    If the drive has important data I would suggest replacing it or at least ensure you have a backup in place. It's also possible nothing will ever happen and the drive would be fine. You could also disable head parking to theoretically extend the drive life.

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  5. I guess I am the only one who comes here to share my very own experience guess what? I am using my laptop for almost the post 2 years.

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