Storage forum

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Bad sectors and bad clusters.

by christy / October 29, 2007 12:25 AM PDT

chkdsk found bad clusters on my HD, and replaced them. Am I right to understand that this refers to the file system, and no harm has happened as compared to bad sectors being found, where a defect has been discovered, which is marked so that no further data can be written; in which case, free space will be reduced (e.g. when I delete the partition and then recreate it) ? Thanks.


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by Dango517 / October 29, 2007 12:49 AM PDT
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Re Sorry...
by christy / October 29, 2007 6:31 AM PDT
In reply to: Sorry

Thanks for the information. Well, its strange then. Subsequent checks showed no bad sectors ! That is why I asked. I thought "sectors" (a section of the surface of the HD ?) and "clusters" ( a group or bundle of files ?) are different.


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May I suggest. . .
by Coryphaeus / November 1, 2007 9:53 PM PDT
In reply to: Re Sorry...

planning on replacing the drive? If you're getting these messages the drive may be going south. I recommend you start backing up your important data, this drive could fail without warning.

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by Dango517 / November 1, 2007 10:01 PM PDT
In reply to: Re Sorry...
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Bad Sectors & Clusters
by WAArnold / November 9, 2007 10:06 AM PST

You didn't say how old the disk is. However, you can get those bad indications in quite a few ways; bumping the computer, banging on the desk during your game playing, getting a power hit, turning the power off wrong, etc., I think you get the picture.

You can have, and most likely do have, bad clusters, sectors on new disks. There are a good number of available spots for those bad clusters,sectors to be changed to and is provided for the specific purpose you are facing. I don't recall the number but there are hundreds available on a disk.

I would suggest you query your method of operation and see if you are causing the problem. If not, keep a check to see if there are recurring instances on a regular basis. If so, get a new disk. It is also possible that you have a controller going bad.

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Bad sectors & clusters.
by christy / November 9, 2007 11:15 AM PST
In reply to: Bad Sectors & Clusters

Thank you for your input.

I am familar with what can cause bad sectors...

The drive was an external drive, 2.5", USB powered 120G for a laptop. When I got the error, I removed the partition, ceated a new one then formated it. Then chkdsk showed no bad sectors, which should have been shown. However, out of 120G, some 4G has been used after creating the new partition and with no data on it. Maybe those bad sectors have been marked as used area ? In have since purchased a new drive.

Collapse - one else mentioned this so I will
by Bdubslawman / November 12, 2007 7:12 PM PST

"Then chkdsk showed no bad sectors, which should have been shown..."
I have been a disciple of Steve Gibson (another poster recommended his product Spinrite)....anyway. One of the many downfalls of Bill Gate's poorly designed OS is that something like Chkdsk is simply too blunt tool to be of more than slight use.

Once Chkdsk has "found" what "it thinks is a bad sector" it makes NO ATTEMPT to verify this, it simply marks that sector bad and reallocates use to the set aside sectors that are allocated for use when bad sectors are "detected". So once detected, You in fact should never ever see this sector re-detected as bad. Because as far as the drive is concerned / and your OS are concerned that sector is dead to them. Unless you use a more advanced program that has access to all the sectors and can do some more thorough examination.

In regards of the "missing 4GBs" in a 120GB drive.... I assume you are aware of the 1000 vs 1024 KB conversion issue, right? If not You can google an answer about missing disk space or you can check out this article:
A 120GB Hard drive will typically show up around 112GB - 115GB due to this "trick".

If the 4GB is in addition to that then I would use the software from whatever brand of hard drive you have and re-setup your HD making sure that you don't have any un-allocated space on the drive. (This is different than just re-formatting. As this will make sure there is no unallocated space hiding as a result of the partition change).

Hope this helps. I won't be back to see if it did so good luck.

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Spinrite: Data recovery & Disk repair software
by chucknobucks / November 9, 2007 1:47 PM PST

Here's the link:

Spinrite will detect bad sectors, recover the data (if possible), migrate it to a good sector and quarantine the bad sectors so they won't be written to again.

It will also diagnose the overall health of your drive and warn of impending doom.

Works on hard drives and floppy drives too. If anybody still uses floppies.

Many more features and an explanation of the processes involved at the website.

A little spendy at $89, but worth every penny if it detects a bad drive in time for you to save your data.

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Other data recovery software available
by Dango517 / November 9, 2007 11:23 PM PST

Some for free.

What is the make of your hard drive? You can find out by: start> control panel> administrative tools> computer management> device manager> click [+] sign next to disk drives, choose internal hard drive(s) from list. Search for the manufactures web site using the search term you find here. Once you get there search for drivers and diagnostic software for it/them. Run diagnostic software for bad sectors and clusters. If none are evident then this could be corruption in the OS that is causing the problem or a problem within check disk. Do a defragmentation and run check disk again. Do you have registry repair software? If so, run this as well.

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