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My laptop seems to have a bizarre problem with the hard drive. The system operates without problems for several months, then the hard drive begins to cause problems, with sector reallocations causing the system to lock up for several seconds and possibly crash with a BSOD. The system may fail to boot at all, not detecting the hard drive. However, if I wait a few minutes, reseat the hard drive SATA connection, and wait a few minutes again, the system will work normally again, until the cycle starts again several months later.

Could this problem be caused by the SATA cable or connections, rather than the hard drive itself? What should I do?


  • Diagnostics have repeatedly passed, and the SMART status is OK.
  • More than 400 sectors have been reallocated, but the reallocated sector count has not failed and is not expected to fail soon.
    • The SMART data indicates that the drive has 80% of its spare sectors left; the threshold is 10%.
  • CrystalDiskInfo says Caution, not Bad as with a drive that has a failing SMART status.

The hard drive is a Toshiba MK6465GSX (640 GB, 5400 RPM), factory-installed as part of a custom-built HP Pavilion dv6z-3000 Select Edition laptop.

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laptops don't have a sata 'cable' and connectors are soldered in so, if it was there, it would be not something easily user servicible. Got a dump file to look at - if it contains the BSODs, it would make it easier to track down? – Journeyman Geek Oct 13 '12 at 1:21
@JourneymanGeek: There is a physically detachable SATA cable on my laptop. The cable is a very short bundle of wires that inserts into the hard drive's SATA pins on one end and into a special, proprietary, connector on the motherboard on the other end. It can easily be obtained from the HP Parts Store as part of the Hard Drive Hardware Kit, which is listed in the laptop's service manual. – bwDraco Oct 13 '12 at 1:38
ahh, thats new to me. Then again, I haven't opened up a laptop with sata yet ;p – Journeyman Geek Oct 13 '12 at 1:44
@JourneymanGeek: Here's a picture of the hard drive, connectors, and SATA cable: – bwDraco Oct 13 '12 at 2:35
Is the drive still under warranty ? If yes, replacing it and the cable is the best solution. – harrymc Oct 13 '12 at 7:41

Sector reallocation happens on all hard drives. It's never a good sign. I'm even more worried by the fact that it happens in bursts on your case: it sounds to me like the drive is more even more prone to failing. After all, sector reallocation is a security mechanism: it's there to avoid crashes and prevent failure, not cause them.

Could SATA communication issues cause the hard drive to reallocate sectors?

Sector reallocation occurs when a bad sector is detected: Let's take a look at Wikipedia's article on bad sectors:

A bad sector is a sector on a computer's disk drive or flash memory that cannot be used due to permanent damage (or an OS inability to successfully access it), such as physical damage to the disk surface (or sometimes sectors being stuck in a magnetic or digital state that cannot be reversed) or failed flash memory transistors. -Wikipedia

A little vague, but I can assume that it is possible for a communication failure between the hard disk and the system to end up marking a sector as "bad".

Modern hard drives present a consistent interface to the rest of the computer, no matter what data encoding scheme is used internally. [...] That DSP also watches the error rate detected by error detection and correction, and performs bad sector remapping, data collection for Self-Monitoring, Analysis, and Reporting Technology, and other internal tasks. -Wikipedia

The hard drive's electronics control the movement of the actuator and the rotation of the disk, and perform reads and writes on demand from the disk controller. -Wikipedia

This roughly means that the hard drive's internal functions are not directly accessible by the controller or the operating system, but only managed by the on-disk controller. One can assume that even a faulty controller could be to blame for the issues that you're facing.

The short answer is "probably, but most likely not". If the on-disk controller can't read a command successfully, it shouldn't do actions that could cause excessive wear on the hard disk.

What should I do?

Unfortunately, you can't open a hard drive and fix an internal failure or fix a motherboard controller at home.

  • Despite all of the above, there is still no way of knowing how tightly connected the problem of sector reallocation (1) and the problem of the hard disk not being detected (2) are. If we assume that (1) is irrelevant, an idea would be to clean all the metal contacts involved in its connection with the motherboard using pressurized air and alcohol on a cotton swab. Make sure no cotton is left on the board.
  • Be careful when transporting the laptop.
  • Run CHKDSK (if you're running a Microsoft OS), or badblocks and fsck (if not) regularly.

However, you can't truly have an answer until you swap this hard disk for another; and this is what I recommend, especially if you keep important data on it.

If the hard disk is under warranty, you might even be able to RMA it. The bad sector issues might be covered by the manufacturer, so contact them and explain the problem.

If the new hard disk still fails, the problem is almost certainly on the motherboard end, which from my experience, is less likely.

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up vote 2 down vote accepted

After spending many months dealing with this issue, I've decided that it's the drive that's at fault. I ended up buying a 640GB WD Scorpio Blue and performed a block-level copy of the drive using dd on a Linux live CD, with the stock drive in the laptop and the new drive in an external enclosure attached via eSATA. The two drives have exactly the same number of sectors, so the copy succeeded without any capacity issues. Then I installed the WD drive onto the laptop and started up the system. An extra reboot was needed for the system to recognize the new drive, but then the system was up and running without any issues.

The new drive is noticeably quieter (seeking is nearly silent) and has better performance than the Toshiba drive—based on disk activity lights, the WD drive increasingly outstripped the Toshiba towards the end of the dd copy, but proved faster throughout the entire copy process. The disk subscore for the Windows Experience Index went up one tenth of a point, from 5.8 to 5.9.

It's probably more reliable, too, since the WD drive uses Advanced Format, unlike the Toshiba (note that the partitions were on 4K boundaries to begin with, so there's no alignment issues to deal with). Since Advanced Format enables more advanced ECC algorithms, this should mean fewer reallocated sectors and improved performance in the long run. The Toshiba was buzzing at several points during the copy with attendant reduction in activity from the WD drive as the old drive redirected reallocated-sector reads, which explains why the disk would intermittently buzz while the system was running, and explains the hangs mentioned in the question.

The lesson to be learned here is that hard drive problems are more prevalent than one might expect, and that reallocated sectors are caused by the drive itself and have nothing to do with SATA communication. I guess I was wrong when I suspected that the SATA cable was faulty...

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Start by running diagnostics on the drive. Most manufacturers have a utility that you can download and test the drive. These do more than just SMART. Identify the drive manufacturer and grab their utility.

Many laptop makers have disgnostic utilities as well. Dell HP and Lenovo do and I assume others. These utilities would allow you to test the controller and other components.

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Diagnostics have repeatedly passed, and the SMART status is OK. More than 400 sectors have been reallocated, but the reallocated sector count has not failed and is not going to fail soon (the SMART data appear to indicate that there are 80% of the spare sectors remaining; the threshold is 10%). CrystalDiskInfo says Caution, not Bad as with a drive that has a failing SMART status. – bwDraco Oct 10 '12 at 16:53
What else can I do to isolate the problem? – bwDraco Oct 11 '12 at 17:55
Having any reallocated sectors will dramatically reduce performance on the drive. I would recommend RMA the drive if it is still under warranty. – Mike Oct 12 '12 at 23:32
SMART status isn't very reliable. [… found that SMART by itself wasn't a good predictor of drive failure. – Alan Shutko Oct 15 '12 at 17:21

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