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Chris Hoffman is Editor-in-Chief the How-To Geek. He"s composed about modern technology for over a decade and was a PCWorld columnist for two years. Chris has written because that The brand-new York Times, been interviewed together a technology expert top top TV stations like Miami"s NBC 6, and had his job-related covered by news outlets choose the BBC. Since 2011, Chris has actually written over 2,000 posts that have actually been read practically one exchange rate times---and that"s just right here at How-To Geek. Check out more...

You are watching: How many bad sectors are too many

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UpdatedJul 5, 2017, 6:13 pm EDT| 4 min read

A poor sector top top a tough drive is merely a tiny cluster of storage space — a ar — the the hard drive that appears to it is in defective. The ar won’t answers to review or write requests.

Bad sectors can occur on both traditional magnetic hard drives and modern-day solid-state drives. There room two varieties of bad sectors — one resulting from physical damages that can’t it is in repaired, and also one resulting from software errors that have the right to be fixed.

Types of bad Sectors

There space two varieties of poor sectors — often divided into “physical” and “logical” bad sectors or “hard” and “soft” bad sectors.

A physical — or hard — bad sector is a swarm of warehouse on the tough drive that’s physical damaged. The hard drive’s head may have touched that part of the tough drive and damaged it, some dust might have worked out on that sector and ruined it, a solid-state drive’s flash memory cell may have worn out, or the difficult drive might have had other defects or wear concerns that resulted in the ar to come to be physically damaged. This kind of sector cannot be repaired.

A logical — or soft — negative sector is a cluster of warehouse on the tough drive that shows up to no be working properly. The operating device may have tried to read data ~ above the difficult drive native this sector and also found the the error-correcting password (ECC) didn’t enhance the contents of the sector, which suggests that other is wrong. These may be significant as poor sectors, yet can be repaired through overwriting the drive v zeros — or, in the old days, performing a low-level format. Windows’ Disk inspect tool can additionally repair such poor sectors.

Causes the Hard poor Sectors

Your difficult drive may have shipped indigenous the manufacturing facility with bad sectors. Modern manufacturing approaches aren’t perfect, and there’s a margin or error in everything. That’s why solid-state drives often ship through some defective blocks. These are significant as defective and also are remapped to several of the solid-state drive’s extra memory cells.


On a solid-state drive, herbal wear will eventually result in sectors becoming poor as they’re composed to countless times, and they’ll it is in remapped come the solid-state drive’s extra — or “overprovisioned” — memory. When the solid-state drive’s extra storage runs out, the drive’s capacity will start to drop together sectors become unreadable.

On a timeless magnetic tough drive, negative sectors have the right to be brought about by physical damage. The tough drive may have had a production error, natural wear may have actually worn component of the hard drive down, the drive may have been dropped, resulting in the tough drive’s head to touch the platter and damage several of the sectors, part air might have entered the sealed area of the tough drive and the dust may have actually damaged the journey — there space many possible causes.


Causes of Soft bad Sectors

Soft poor sectors are brought about by software application issues. For example, if your computer system suddenly shuts off because of a power outage or a pulled power cable, it’s feasible that the difficult drive may have shut turn off in the middle of writing to a sector. In some cases, it’s possible for sectors top top the tough drive to contain data the doesn’t enhance their error-correction code — this would certainly be marked as a negative sector. Viruses and also other malware that messes with your computer could additionally cause such device issues and cause soft poor sectors come develop.

Data Loss and also Hard journey Failure

The truth of poor sectors brings house a chilling reality — even if your hard drive is otherwise functioning properly, it’s feasible for a bad sector to develop and also corrupt several of your data. This is an additional reason why you must always ago up her data — multiple duplicates are the only thing that will certainly prevent negative sectors and also other worries from destroying your tough drive’s data.

RELATED: How to check out If Your difficult Drive Is Dying through S.M.A.R.T.

When your computer notices a poor sector, that marks the sector as bad and also ignores the in the future. The sector will certainly be reallocated, therefore reads and writes to the sector will certainly go elsewhere. This will show up together “Reallocated Sectors” in difficult drive S.M.A.R.T. Analysis tools favor CrystalDiskInfo. If friend had vital data in the sector, however, it might be shed — maybe corrupting one or an ext files.

A few bad sectors don’t indicate that a difficult drive is about to failure — they deserve to just happen. However, if your hard drive is rapidly developing bad sectors, it might be a sign that your tough drive is failing.

How to examine for and also Repair poor Sectors

RELATED: How to Fix hard Drive problems with Chkdsk in home windows 7, 8, and also 10

Windows has a integrated Disk inspect tool — likewise known as chkdsk — that deserve to scan your tough drives for negative sectors, marking tough ones together bad and repairing soft ones to make them usable again. If windows thinks that there’s a trouble on your tough disk — due to the fact that the difficult drive’s “dirty bit” is collection — the will automatically run this tool as soon as your computer system starts up. But you’re also totally free to run this tool manually at any point.

Other operating systems, consisting of Linux and also OS X, also have their own built-in disk utilities for detecting poor sectors.

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Bad sectors are just a reality of difficult disks, and there’s typically no factor to panic as soon as you encounter one. However, you should always have backups of your important papers just in case a freak negative sector strikes — and rapidly occurring bad sectors can certainly suggest oncoming difficult drive failure.

Image Credit: Jeff Kubina ~ above Flickr, moppet65535 ~ above Flickr

Chris HoffmanChris Hoffman is Editor-in-Chief the How-To Geek. He"s composed about modern technology for end a decade and also was a PCWorld columnist for 2 years. Chris has written for The new York Times, been interviewed together a technology expert top top TV stations like Miami"s NBC 6, and had his occupational covered by news outlets like the BBC. Because 2011, Chris has written over 2,000 articles that have been read practically one exchange rate times---and that"s just below at How-To Geek. Read full Bio »