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I grabbed this information from Disk Utillity on Linux Mint:

Current Pending Sector Count:

Normalized: 200
Worst:      200
Threshold:  0
Value:      22 sectors

What does it mean? Is it possible to fix that error?

3 Answers 3

9

It means that there are 22 sectors that could not be read. The next time you write to those sectors, if they can not be correctly written to, they will be remapped to a spare sector. You can use the badblocks utility to locate the bad sectors, and dd to write to them:

sudo badblocks -b 512 /dev/sda

For each sector listed, first verify that it can not be read:

sudo dd if=/dev/sda of=/dev/null bs=512 count=1 iflag=direct skip=[sector]

This should fail with an IO error. If it does, proceed with writing:

sudo dd if=/dev/zero of=/dev/sda bs=512 count=1 oflag=direct seek=[sector]

Use the sector number given by badblocks for [sector]. After doing this, check the SMART stats again and the pending count should be zero. The reallocated count might rise in the event that the writing failed and the sectors were reallocated from the spare pool. If this happens, you may want to replace the disk. If it does not, then all has been repaired.

4

The current pending sector count is the number of sectors the disk is currently tracking that it has not been able to read. With luck, they'll be written, and then the disk will remap them. But until it reads them successfully or the computer tries to write to them, there's nothing it can do. This is a possible sign of more problems to come.

You can read more about SMART on Wikipedia.

1

Perhaps a safer way to remap individual sectors is by using hdparm:

$ sudo hdparm --read-sector 12345678 /dev/sdx # verify that there is a read error
$ sudo hdparm --yes-i-know-what-i-am-doing --write-sector 12345678 /dev/sdx

Unlike dd, hdparm is designed to work with single sectors, so there's less chance that it trashes half of your disk due to a typo.

In addition to badblocks, already known unreadable sectors are reported in the kernel log (dmesg | grep sector) or in SMART reports (smartctl -x). If the number of such sectors is so high that it's unpractical to remap them by hand, I would actually consider replacing the HDD as it is a sign of an imminent permanent failure.

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