Technical help - bad sectors

  johndrew 12:40 12 Nov 09
Locked

Yesterday I carried out an Acronis TI backup but part way through I received a message that `sector 155 970 831 failed to read` because it was bad and gave the options to `try again/ignore/ignore all/cancel`, I selected `ignore` and ATI completed the backup which validated OK.

I then ran CHKDSK to fix errors and scan and attempt/fix bad sectors. It ran to completion and advised that it had replaced file \system~1\restore~1\rpf38\a0213200.dll in cluster 139356 - or something similar.

From the above I think I understand that a part (sector?) on he drive has failed(?) and is not useable. Given that I am aware that a level of redundancy is present in drives this doesn`t appear to be a massive problem. However, what if I defrag the drive, is the `bad` bit marked as unusable or will there be an attempt to write to it that will cause a similar ATI report and a need for CHKDSK to be run again?

Please will one of the more technical members here explain/advise how such problems are dealt with by the software in very simple terms?

Many thanks in anticipation.

  Seth Haniel 13:31 12 Nov 09

a bad sector could be caused by pc shutting down unexpectedly - chkdsk marks these sectors so that they will be missed by writing to the disk. The file affected there is in one of the system restore files so no great loss - if you do a defrag with the view pane open you will see that it marks bad sectors in 'red' so you can see how many or how big they are - only if there are quite a few should you worry as disk could be on way out

  Pamy 13:43 12 Nov 09

Download and make a diagnostic disk from the HDD makers web site and then check out your disk. If your bad sectors keep increasing over a few months then it is time to replace the HDD

  johndrew 14:23 12 Nov 09

Many thanks for coming back people.

I think you are both concerned that I`m worrying about the drive; I`m not. My concern is purely about the effect of a defrag on any `marking` of bad sectors; ie is it possible for the defrag process to permit software (OS) to attempt to write to them in the future causing problems?

I think from what Seth Haniel says, ".. if you do a defrag with the view pane open you will see that it marks bad sectors in 'red' so you can see how many or how big they are .." the answer is "no" but confirmation would be appreciated.

  Pamy 14:28 12 Nov 09

The sectors will be marked as bad and will not be used by any software, but be aware your disk may be failing

  johndrew 14:42 12 Nov 09

Thanks Pamy.

I use HDD Health to keep an eye on my drives and for this drive it reports, "Current Pending Sector Count (Unstable Sectors) 1 sectors. Uncorrectable Sector Count 0 sectors." and the drive is fairly new so I have confidence in it currently.

Perhaps I should add the current prediction status is given as 97% with a current T.E.C. (`end of life) of 2094 so things don`t look that bad. Unless of course you know of a reason I should be concerned?

  Pamy 15:47 12 Nov 09

I would still use the makers diagnostic software

  johndrew 16:20 12 Nov 09

Thanks Pamy, noted.

  john bunyan 16:46 12 Nov 09

When you do an ATI image or clone, do you run through the "verify" step? I had a similar problem to yours and got into a terrible mess restoring from an unverified image (stopped it half way through!). Luckily, I also had a clone so disaster was avoided. I had not, before advice here, realised the importance of the verify step Now, prior to making a back up image, I scan with AVG 8.5, SAS and Malaware bytes, then defrag, then go through the ATI routine.

  johndrew 09:47 13 Nov 09

Yes, I always verify every backup. But I do it as a seperate function not combined with the backup. As you say, without the verification the backup can be damaged with no indication.

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