Comment 211 for bug 59695

Chris Jones (cmsj) wrote :

This issue has been extensively covered in the press recently and, as should be blindingly obvious by now, is, by and large, nonsense.

First of all, let me make this absolutely clear - you should pay ZERO attention to the number reported by smartctl for Load_Cycle_Count. It is probably not a raw counter showing the number of times your drive heads have unparked. If you don't believe me, look at this output from my Thinkpad X40:

193 Load_Cycle_Count 0x0032 070 070 000 Old_age Always - 3037783573354

That number is over 3 *trillion*, which, for a 14 month old laptop is physically impossible, it would have to be unparking the heads 80,000 times *a second*. Again, this is physically impossible.

What you should be paying attention to are the THRESH, VALUE and WORST columns. This is an Old_age SMART value, so the VALUE starts at 100 and counts down to 0. When it crosses THRESH it means your drive manufacturer believes your drive has reached the end of its probable lifespan.

So, in my above example, the THRESH, VALUE and WORST columns are 70, 70 and 0 respectively. In this case VALUE and WORST will always be the same because it's simply counting down over time and in this case, I have used about 30% of the expected lifespan of my drive, which, at 14 months and it being a rubbishy 1.8" laptop drive, seems entirely reasonable.

My value will be lower than a stock install would because I've had laptop_mode enabled for at least a year, so the heads are unparking quite aggressively.

So, to be absolutely, entirely clear about this, Ubuntu is not killing my hard disk, no matter what Slashdot and misinformed blog posts claim.

To everyone who has commented on this bug with wild claims about how much their Load_Cycle_Count value is increasing, go back to smartctl's output and check the VALUE and THRESH columns and I am entirely confident you will find that your drive is well within expected lifespan.

The reason is because the RAW_VALUE column is entirely manufacturer specific. A few drives will actually report a counter of the number of times they've unparked the heads, but many/most report something that we have no idea about the meaning of. It's not a meaningful number. SMART is not designed to report meaningful numbers like that, it is designed to provide an indication of health that is interpreted by the firmware on the drive itself, this is what the VALUE, THRESH and WORST columns are for. Use them.