Can prematurely powering down a computer cause bad sectors in a hard drive?

Q1: Can forcibly powering off a PC without using the built-in shutdown/reboot functions, cause a HDD to accumulate bad sectors? Whether it be the result of BSODs, lockups, crashes, etc.

No. It can result in data corruption because the applications and OS did not have enough time to write pending information in memory to the disk. But it cannot result in bad sectors - all HDDs have built-in "retract circuits" that autopark the heads safely when powered off. See "Can sudden shutdown of pc can make BAD sector in HDD?"

Q2: If so, are these bad sectors repairable? I know an OS typically relocate bad sectors to other areas of the drive, but once a drive accumulates too many it just dies.

Firstly, the OS does not relocate bad sectors. The drive's firmware relocates bad sectors transparently to the OS if it finds that it's unable to reliably write to a location. Secondly, there is no "repairing" of bad sectors whose error rates are higher than what the drive's error correction mechanisms can handle. Truly bad sectors can only be relocated to a spare area of the drive (as you stated).

Reference: Error detection and correction

In any case, you should not forcibly power off a computer if you value your data. It can result in OS crashes, application crashes and loss of data.

To add to the information on autoparking HDD heads, here are a few patents (several years to decades old) related to retract circuits on HDDs (see other patents referred to within these as well):

M K

Posted 2013-09-17T06:49:04.627

Reputation: 2 414

Disk driver wont "fix" bad sectors, but it should mark them as bad (unusable) and therefore no data would be written to those bad sectors. – Ashildr – 2013-09-17T08:22:44.310

2@ M K: Thanks for you answer, it was the most concise so far. The TomsHardware website was particularly helpful. And just so you know, my forced poweroffs were basically crashes. That's what I meant. I always use the shutdown function otherwise. But this still leaves my wondering how 2 drives can die on me in one laptop in just a year's time. And recently I bought another laptop, it's drive died within a week of purchase. Thankfully I was still within the refund policy and got an exchange. No problems so far. Thanks! – Enigma83 – 2013-09-17T16:52:30.437

Maybe they died due to some other reason? Do you clean your laptop (especially the fan vents) regularly to ensure that it doesn't overheat? You could also run smartmontools on the drives regularly to see what the drive sees in terms of usage, errors, etc. There are also GUI tools for monitoring drives. If the answer was useful, you could accept it, unless you'd like to wait for better answers.

– M K – 2013-09-17T17:41:21.320

I thought that hard drives used the momentum of the spinning disk to provide energy to park the heads, not capacitors. – cmorse – 2013-09-20T19:02:14.473

I've updated my answer based on more research and have added patent references too. It's actually called a retract circuit. It does not use mechanical energy from the spinning disk directly to move the heads, but converts that to electrical energy, which is then used by the retract circuit to move the heads safely. – M K – 2013-09-21T06:06:34.333

My guess would be that constructors have built systems in that case, like condensators used as mini-UPS to power-down the drive gracefully even with the cable pulled out. But that would be the physical side of the problem. The software side remains full. – mveroone – 2013-09-17T07:24:36.193

1If I may add, programs reading the S.M.A.R.T. records of your drive will tell you wether you have "bad sectors" or any other damages in yourd rives. Speedfan for example can read SMART – mveroone – 2013-09-17T07:26:00.560

Possible duplicate of http://superuser.com/questions/6863/what-damage-will-powering-down-instead-of-shutting-down-do or http://superuser.com/questions/433994/does-shutting-down-regularly-harm-laptop-or-windows That's just two posts found after googling: (power down) or (shut off) site:superuser.com

– Jan Doggen – 2013-09-17T08:53:41.800

1@ Kwaio: I know about SMART and how it can be used to monitor the health of a drive. Ongoing tests that the drive I'm currently running fine is fine, with no bad sectors. Thanks anyway! @ Jan Doggen: I did Google before I posted, the result you listed didn't appear. But I just read them and they are are too vague (when compared to my question, which is very specific) and dont quite ask the same thing as me. Hence my post here. – Enigma83 – 2013-09-17T16:45:25.280

Can prematurely powering down a computer cause bad sectors in a hard drive?

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