If I copied some files from a hard disk with bad sectors without errors, are those files unaffected?

Or do I have to find a backup?

It had thousands of reallocated sectors.

I ran badblocks on one partition but not others. Does that change the result?

I'm using Ubuntu. Some partitions are ntfs and some are ext4, if that matters.

Edit:

I believe the the bad sectors are because of it fell down to the floor for many times.

The first partition is a Ubuntu installation (for boot repair, or using Ubuntu on someone else's computer, etc), which has nothing important and I didn't use it for maybe at least a year. I didn't feel anything strange until one day I failed to boot a computer using it.

I ran badblocks on two partitions, and found thousands of errors mostly only on that partition. But it is very slow when reading some files on the second partition, which is why I'm concerned.

I didn't check other partitions yet because it becomes obvious I will replace this disk, and I'm afaid of making things worse by reading and writing for more times.

user23013

Posted 2015-08-27T11:27:56.487

Reputation: 167

2If you are asking if those files are corrupt, only you can answer that, by verifying if the files are not corrupt yourself. – Ramhound – 2015-08-27T11:43:14.677

@Ramhound Did you mean that, if the files are corrupt, it may return garbage data silently without reporting any errors? Then what are the ECC for? Only for correction, but I cannot know whether it is possibly corrupted? – user23013 – 2015-08-27T12:32:15.590

ECC only works if corruption can be detected and correct. A bad sector that isn't guaranteed. You can detect corruption by comparing it to a known good copy. – Ramhound – 2015-08-27T12:36:52.880

@Ramhound Is there any technical informations about how it is likely undetectable and corrupted? I don't have known good copies for every file. And some files are from hundreds of old CD-ROMs I wanted to get rid of, and I really don't want to backup those again. – user23013 – 2015-08-27T12:45:01.940

I don't know where your confusion is with my statements so I can't help. There are soft sector failures and hard sector failures. In the case of a soft sector failure, the HDD thinks the sector is bad, when it actually isn't. In the case of a hard failure, no amount of attempts to trick the HDD, will make the sector good. In a hard failure you normally have mechanical problems also. – Ramhound – 2015-08-27T12:47:25.213

@user23013: ECC detects and sometimes corrects errors. Undetected errors on modern drives are extremely rare to the point that they may as well never happen. The whole reason a bad sector exists is because the ECC detected corruption. – qasdfdsaq – 2015-08-27T12:51:22.660

This is only true if the HDD can detect the corruption. There is a non-trivial chance that a HDD with this many bad sectors, would not know the sector was actually bad until the file couldn't be read. – Ramhound – 2015-08-27T12:50:35.047

It sometimes doesn't report any errors, but runs very slowly. I think at least it tried to recover some damaged data, but I'm not sure how much confidence I should have about the recovered result. – user23013 – 2015-08-27T12:52:06.897

@user23013: The recovered result is 100% accurate. – qasdfdsaq – 2015-08-27T13:06:06.050

@qasdfdsaq If you can expand it to an answer and maybe add some reference, I can accept your answer. (Preferably also whether badblocks will damage data or suppress further error reports, but I may post another question if you think that's irrelevant.) – user23013 – 2015-08-27T13:14:01.337

If I copied some files from a hard disk with bad sectors without errors, are those files unaffected?

Answers