How SMART is Your Hard Drive?

Category: Hard-Drives

Readers often ask me, 'How long will a hard drive last?' The answer is indeterminate, as I’ve explained in the recent past. But some factors can be monitored to provide the user with early warning that it’s time to get serious about making frequent backups and shopping for a new drive. Learn more about S.M.A.R.T. and other tools to monitor the health of your hard drive...

Hard Drive Health Check

Over time, hard drive makers have learned that there are traits of a hard drive that change as it approaches failure, providing tell-tale signs that a data disaster may be approaching. The industry standard for hard drive “failure anticipation” is called Self-Monitoring And Reporting Technology, or S.M.A.R.T. for short. In this article you'll learn how it works, how you can take advantage of it, and if it's a reliable indicator of the condition of your hard drive.

If you missed my earlier article How Long Do Hard Drives Last?, I encourage you to read that first, to learn about hard drive life expectancy and why I think that's really the wrong question to be asking.

Hard disk failures arise from two general types of factors: 1) sudden, unpredictable catastrophes such as falls onto concrete floors or zaps from cosmic rays, and 2) gradual, relatively steady deterioration of mechanical components until one of them fails. About 60 percent of disk failures are due to the latter, predictable sort of factors; these are what S.M.A.R.T. monitors.
SMART failure warning message

Traditional hard drives employ spinning magnetic platters, and S.M.A.R.T. monitors the rate at which the bearings under them are wearing, for instance. Using that rate, S.M.A.R.T. predicts when a bearing will be worn to a specified degree, called the “threshold value” for bearing wear. When S.M.A.R.T. determines that a bearing is X days from that threshold value, it generates an alert that effectively says, “Captain, she’s about t’blow!”

Dozens of such factors can cause a hard drive failure and are written into the S.M.A.R.T. standard. Every drive manufacturer is free to choose which factors it wants to monitor and what the failure threshold values will be for its drives. S.M.A.R.T. has evolved through three phases. The current phase goes beyond monitoring and reporting to actively attempt to prevent or forestall drive failures. Modern S.M.A.R.T. drives will try to “heal themselves” by reallocating data from disk sectors that are near failing to reserved “spare areas.” They still can’t change their own bearings, though.

How Can I View My S.M.A.R.T. Reporting?

For a quick look at your hard drive's S.M.A.R.T. status, try the free Speccy utility. In the Hard Drives section of the Speccy results, you'll see some technical gibberish under the S.M.A.R.T heading. If it says "Status: Good" at the bottom, that's about all you need to know. The only other info there you might want to check out is the Reallocated Sectors Count. If that's greater than zero, you may have some defective sectors on your hard drive.

For a more detailed look, you can monitor S.M.A.R.T. factors using software such as Argus Monitor for Windows or Disk Utility for Mac (in the Apple App Store). But before you shell out money for either program, you may want to know just how reliable a predictor of drive failure S.M.A.R.T. really is.

How Smart is S.M.A.R.T?

Google spent nine months monitoring over 100,000 drives back in 2007. A paper entitled Failure Trends in a Large Disk Drive Population reported the results. Four “strong” S.M.A.R.T. factors were identified as the best predictors of drive failure; the bad news is that 56 percent of the drives that failed did so without reporting a threshold level in a single one of these factors. So S.M.A.R.T. data alone is of limited value in predicting when a drive is going to fail.

Another issue is that S.M.A.R.T.’s implementation can (and does) vary widely from one manufacturer to another. There are dozens of S.M.A.R.T. factors that can be monitored, but a manufacturer need only implement one in order to legally call its drive “S.M.A.R.T. compatible.” Some removable drives cannot be monitored at all, or only with certain proprietary software such as Argus Monitor.

The bottom line is that S.M.A.R.T. won’t give you warning of impending drive failure with a high degree of reliability. I would not spend much time monitoring S.M.A.R.T. factors, and I definitely would not spend any money to do it. That said, it does predict failure in some cases, and if you do see a S.M.A.R.T warning along the lines of "SMART Failure Predicted on Hard Disk. Failure may be imminent" it should be taken seriously.

Other Hard Drive Health Tools

A disk checking utility called CHKDSK comes with Windows, and it's pretty good at detecting bad files and physically damaged sectors. It will lock damaged sectors so that the computer will not attempt to write to them. To run CHKDSK, first open the "Computer" window. (On Windows XP, look for My Computer. On Windows 8, it's called This PC.) Right-click on the icon for the hard drive you want to check, and select Properties. On the "Tools" tab, click the "Check Now" button under Error-checking.

In my article Is Your Hard Drive Going to Crash? you'll find links to some free third-party utilities you can use to run more thorough hard drive health tests.

I'll also repeat my bottom line advice from that article: Most of the time, hard drive failures happen at unpredictable and inconvenient times. So backing up your data regularly is vital, and is your best defense against loss of data. My article Free Backup Software Solutions will get you started, if you're not doing backups already.

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Most recent comments on "How SMART is Your Hard Drive?"

Posted by:

06 Feb 2014

Most of us wouldn't be surprised at failure through "...catastrophes such as falls onto concrete floors...", but I lost an external disk when it merely toppled sideways on to a wooden surface. I shudder when manufacturers show their products standing like a book, or even name them as such - although to be fair, "book" was not in the name of my dead disk. Lay your disks flat!

Posted by:

Joseph Fischer
06 Feb 2014

Hard drives are much more reliable now than they were 20 years ago. In the old days, the hard drive would often be the first component to go on a desk top computer and especially on laptops. Working in tech support, it was routine for me to try and reallocate bad sectors on hard drives. It was a common occurrence to replace hard drives. Desktops and even laptops were built so it was easy to swap out a crashed hard drive. (Lost data was a different story.)

Today, unless a laptop is dropped, the screen or the power supply usually fails first, before the hard drive. By then, the computer is usually so old and obsolete, that it isn't worth fixing.

It will be interesting to see how Solid State Drives SSD's hold up over years of use. Since they have no moving parts, they can withstand the shock of being dropped.

Posted by:

Gary Brodock
06 Feb 2014

I am assuming that since I have an SSD, my drive does not have moving parts or SMART technology and I don't have to worry much about failure. Am I correct?

Posted by:

Ives Martinez
07 Feb 2014

Hi Bob, first of all I want to thank you for all the advise that you so freely give to us older folks trying to cope with developing technology. Could you please take a look at the Speccy report of my hard drive and tell me if everything is as it should be? Thank you,

Status Good
Temperature 49 °C
Temperature Range OK (less than 50 °C)
01 Read Error Rate 117 (099) Data 0007D2E3F6
03 Spin-Up Time 099 (099) Data 0000000000
04 Start/Stop Count 099 (099) Data 000000046A
05 Reallocated Sectors Count 100 (100) Data 0000000000
07 Seek Error Rate 072 (060) Data 00024BCB5D
09 Power-On Hours (POH) 098 (098) Data 00000006F1
0A Spin Retry Count 100 (100) Data 0000000000
0C Device Power Cycle Count 099 (037) Data 0000000468
B7 SATA Downshift Error Count 100 (253) Data 0000000000
B8 End-to-End error / IOEDC 100 (100) Data 0000000000
BB Reported Uncorrectable Errors 100 (100) Data 0000000000
BC Command Timeout 100 (100) Data 0000000002
BD High Fly Writes (WDC) 100 (100) Data 0000000000
BE Temperature Difference from 100 052 (042) Data 0030200030
BF G-sense error rate 100 (100) Data 000000001B
C0 Power-off Retract Count 100 (100) Data 0000000017
C1 Load/Unload Cycle Count 093 (093) Data 00000037FD
C2 Temperature 048 (058) Data 0000000030
C3 Hardware ECC Recovered 050 (043) Data 0007D2E3F6
C4 Reallocation Event Count 100 (100) Data 0000000000
C5 Current Pending Sector Count 100 (100) Data 0000000000
C6 Uncorrectable Sector Count 100 (100) Data 0000000000
C7 UltraDMA CRC Error Count 200 (200) Data 0000000000
FE Free Fall Protection 100 (100) Data 0000000000

EDITOR'S NOTE: As I mentioned, you're looking for "Status Good" and Reallocated Sectors Count=0. You got both.

Posted by:

Art Frailey
07 Feb 2014

BACK IT UP ! Then don't worry about the monster blowing up or getting drop kicked. It is only about $100 to replace. What do these dumb programs cost, that often like S.M.A.R.T., just do not get the frustrating job done ?

Posted by:

07 Feb 2014

I swear by Defraggler. It includes a file or piece of program that rates the hard drive. Mine always has come up "good", but how much faith can I put in that. Best regards, john.

Posted by:

07 Feb 2014

I didn't pay attention to what was included with my Patriot Pyro SSD, but about six months after purchase an imminent failure warning appeared on screen. I backed up the SSD and emailed Patriot for an RMA. They gave me links to HDtune and Crystal Disk. HDtune confirmed the message I got earlier. (I chose HDtune because Crystal Disk was hosted on CNET.)

Bottom line: made arrangements to return the SSD to Patriot (local to me) and was handed its replacement on the spot.

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