Is he right about scandisk

[Robgeek]

I almost had a heartattack when I read what this Scott Moulton told me regarding checkdisk.
I recently emailed a Scott moulton from myharddrivedied.com and he said in reply about whether or not checkdisk/scandisk does any damage.

I wish microsoft had never put those tools in the system, all it does is
destroy data. Yes, just running the processes destroys data or affects
files. And the process is irreversible.
Scandisk collects clusters that it thinks are damaged based on some very
simple processes where it checks two bytes in the MFT entries and then if
those are not correct it will assume the data is damaged and the block
will be marked Bad and a cluster or file will disappear.
However if it is a bad sector, it is possible I can get it back with
special equipment that is very expensive. I can do things with hard drives
that only maybe 5 people in the world can do. If the data is on there and
it is possible I can get the data back. Local computer guys can't even
fathom the processes I use. If you want to send it in for me to look at I
will do everything I can to fix the problem if its possible. If you would
like to, here are the details below.
Microsofts tool does not repair it deletes and destroys clusters. Yes it would affect video.


What do you think ?, is he right or is he wrong or perhaps exaggerating a bit, please let me know.

 

[VirtualLarry]

Basically, he's right. All scandisk/chkdisk cares about, is filesystem integrity. Not data (file) integrity.

 

[Robgeek]

Basically, he's right. All scandisk/chkdisk cares about, is filesystem integrity. Not data (file) integrity.

Well that sucks big time, why would microsoft do that to us?, would'nt they get sued for something like this?

Can you tell me if I did not click automatically fix file system errors and repair bad sectors is it possible checkdisk would of still deleted/damaged my files?, and if they had actually damaged them would that be noticable?

Theoratically if one were to click those two buttons whats the worst damage scandisk could do?, would it corrupt the harddrive or just delete the data on the harddrive.

I recently scanned a bunch of videos on my portable harddrive and later I found two files were locked and had no data in them, could checkdisk of done this?

Do i have to format the drive now scandisk has done its scan.

 

[Robgeek]

Can you explain this to me please.

Scandisk collects clusters that it thinks are damaged based on some very
simple processes where it checks two bytes in the MFT entries and then if
those are not correct it will assume the data is damaged and the block
will be marked Bad and a cluster or file will disappear.

 

[SOFTengCOMPelec]

You are probably NOT going to like me saying this. But I think the real problem, is that you need to start (if you are NOT already doing this) BACKING up your data. (Making copies of it).
If the only copy of your data, is on your hard drive, then there are many ways, that some or all that information, can vanish, instantly.
E.g. Hard disk failure (common), virus's, user mistakes, poor quality disk checking programs, malfunctioning programs, computer equipment stolen, fire, etc etc.

In answer to your question.

Can you tell me if I did not click automatically fix file system errors and repair bad sectors is it possible checkdisk would of still deleted/damaged my files?

I UNCHECK the options to automatically fix stuff, which usually seems to stop it messing things up.

 

[Robgeek]

You are probably NOT going to like me saying this. But I think the real problem, is that you need to start (if you are NOT already doing this) BACKING up your data. (Making copies of it).
If the only copy of your data, is on your hard drive, then there are many ways, that some or all that information, can vanish, instantly.
E.g. Hard disk failure (common), virus's, user mistakes, poor quality disk checking programs, malfunctioning programs, computer equipment stolen, fire, etc etc.

In answer to your question.



I UNCHECK the options to automatically fix stuff, which usually seems to stop it messing things up.

Good advice, but why would a basic scan mess data up anyway?, I mean what about videos on your os harddrive?, really should'nt a scan only effect the harddrive when its damaged already?, and what sort of damage would one expect.
Its done now I've scanned both my portable harddrives with video, there's no going back I'm just trying to analyze the damage I've possibly done.

Thanks for your help and patience.

 

[SOFTengCOMPelec]

Can you explain this to me please.

Scandisk collects clusters that it thinks are damaged based on some very
simple processes where it checks two bytes in the MFT entries and then if
those are not correct it will assume the data is damaged and the block
will be marked Bad and a cluster or file will disappear.

Translation:
Microsoft inbuilt tools are relatively simplistic, and do NOT do a very good job.

Consider Microsoft Paint, or notepad.
Great for doing a very simple and quick picture or two line message.

But for a 200 page document or wanting to extensively edit 200 complicated camera photographs, those tools would be a VERY bad idea.
You would use a decent word processor, and a decent Photoshop like program, to do that work.

There are better disk checking/fixing programs available, but the real secret is to keep decent backups, because there are big limits on even the best disk utilities, as to how much they can repair.
Often, once the data is gone, it is gone, and no amount of disk utilities will get it back, but sometimes data can be recovered.

 

[SOFTengCOMPelec]

Good advice, but why would a basic scan mess data up anyway?, I mean what about videos on your os harddrive?, really should'nt a scan only effect the harddrive when its damaged already?, and what sort of damage would one expect.
Its done now I've scanned both my portable harddrives with video, there's no going back I'm just trying to analyze the damage I've possibly done.

Thanks for your help and patience.

My opinion is, the defaulting to "auto correct", and the way it sometimes (all too often) messes up, and makes things considerably worse, is a sad reflection on Microsofts quality control. The ultimate cause might be because Microsoft effectively has a monopoly on mainstream operating systems, giving them little incentive, to produce a decent, quality product.
Although, a number of aspects of Microsofts later operating systems, are actually quite good, but unfortunately, they get black marks in a number of areas, including disk checkers.

 

[Robgeek]

Translation:
Microsoft inbuilt tools are relatively simplistic, and do NOT do a very good job.

Consider Microsoft Paint, or notepad.
Great for doing a very simple and quick picture or two line message.

But for a 200 page document or wanting to extensively edit 200 complicated camera photographs, those tools would be a VERY bad idea.
You would use a decent word processor, and a decent Photoshop like program, to do that work.

There are better disk checking/fixing programs available, but the real secret is to keep decent backups, because there are big limits on even the best disk utilities, as to how much they can repair.
Often, once the data is gone, it is gone, and no amount of disk utilities will get it back, but sometimes data can be recovered.

Eeek, thats horrible.
Well I'm going to backup more often, thats for sure.
But I still don't know can scandisk damage files already on the disk and if so to what extent, and would it only really damage if the part of the harddrive was damaged already?, like for a brand new harddrive with videos on it, is there much chance it could get damaged?

 

[Robgeek]

Well what is a cluster?, does scanning my harddrive mean I've ruined the quality of all future videos I put on that harddrive?, and what sort of damage would it do to videos, like specks in the quality or files not playing?

 

[SOFTengCOMPelec]

Eeek, thats horrible.
Well I'm going to backup more often, thats for sure.
But I still don't know can scandisk damage files already on the disk and if so to what extent, and would it only really damage if the part of the harddrive was damaged already?, like for a brand new harddrive with videos on it, is there much chance it could get damaged?

A very quick, rough and somewhat sloppy explanation, is as follows:

Disk utilities (if done properly) is extremely complicated, because there are so many different ways in which the data (especially the catalogue/index which details WHERE the data is, etc) can get damaged or messed up (corrupted).

The Microsoft one, notices that something is wrong, because the details in the catalogue do not match what is on the disk (typically, it is NOT physically damaged, but e.g. the power was switched off while the disks were writing data).
So the utility does a very quick and simple fix, which unfortunately usually erases the data.
But it is possible that quality disk fix utilities "may" be able to still recover some or all of the data.

 

[Elixer]

Um, your blowing things out of proportion.
If you have say a 1GB archive (rar/zip/7zip whatever) and you run chkdsk on it 100 times in a row, since you really, really, are bored, in the end, if you do a integrity test on said archive, it will pass. (heck, you can try 1000, 10,000... and so on)

So when does data loss come into play ? When you don't backup for starters, as was mentioned. When the file system detects corruption (like when you pull the plug on the computer) it then goes and tries to repair the damage. Sometimes it will work, other times, it gets it wrong.
How does it get it wrong ? Too many factors to list, it just does for a variety of reasons.

So, should you worry about running chkdsk ? Nope.
Should you backup important data ? Yep.

 

[SOFTengCOMPelec]

Well what is a cluster?, does scanning my harddrive mean I've ruined the quality of all future videos I put on that harddrive?, and what sort of damage would it do to videos, like specks in the quality or files not playing?

When you have a book, it is split into different 'PAGES'.

So you could consider a cluster as a sheet of paper, where the sheet of paper is stored electronically/magnetically on the disk.

By and large, your disk will be fine for new data (in extreme circumstances, you would need to re-format it, BUT be VERY CAREFUL, as formatting erases ALL the data on the disk).

If (video) files are damaged, usually they would either NOT play at all, or would play for a bit, and suddenly freeze or produce an error message.

 

[SOFTengCOMPelec]

Um, your blowing things out of proportion.
If you have say a 1GB archive (rar/zip/7zip whatever) and you run chkdsk on it 100 times in a row, since you really, really, are bored, in the end, if you do a integrity test on said archive, it will pass. (heck, you can try 1000, 10,000... and so on)

So when does data loss come into play ? When you don't backup for starters, as was mentioned. When the file system detects corruption (like when you pull the plug on the computer) it then goes and tries to repair the damage. Sometimes it will work, other times, it gets it wrong.
How does it get it wrong ? Too many factors to list, it just does for a variety of reasons.

So, should you worry about running chkdsk ? Nope.
Should you backup important data ? Yep.

This!

 

[fzabkar]

Scott Moulton's statement that "I can do things with hard drives that only maybe 5 people in the world can do" says it all, really. In fact the HDD Guru forum is full of professionals who would run rings around him. Hell, any TV repairman knows more about electronics than he does.

AIUI, the problem with modern HDDs is that they develop "weak" heads rather than bad sectors per se. Disc tools such as Chkdsk will decide that a bad sector is irrecoverable and will "repair" the file system instead. In fact I have seen the damage that Chkdsk and other MS tools have done in numerous threads in several storage forums.

Data recovery firms have hardware disc imagers that are able to image by head. That is, in the case of a bad head or two, the affected head(s) can be switched off and the remaining disc surfaces can be cloned. After a head swap, the "bad" surfaces can then also be cloned. The best freeware tool for cloning a failing HDD is ddrescue.

BTW, Scandisk was included in MS-DOS and Windows 9x. It knows nothing about NTFS and MFTs.

 

[Mushkins]

Scott Moulton's statement that "I can do things with hard drives that only maybe 5 people in the world can do" says it all, really. In fact the HDD Guru forum is full of professionals who would run rings around him. Hell, any TV repairman knows more about electronics than he does.

This is pretty much where the guy lost any and all credibility, waiving his self described credentials around like they mean he knows what he's talking about.

OP, you're overreacting. You already got your answer about this in the other thread you made about it. Running CHKDSK does not damage files in and of itself. Running CHKDSK on a 100% healthy disk is going to come back clean and make no changes, period. If your video file was *ALREADY* damaged in some way, or the MFT was damaged and the file cannot be read, depending on how it is damaged CHKDSK can attempt to repair it but as others said it's repairing the file table, it doesnt care about the integrity of the file itself nor could it. Just moving files back and forth from drive to drive runs the risk of an erroneous copy and a corrupted file, there's no reason to believe CHKDSK maliciously ruined those files, and no evidence pointing to that being the root cause.

If you have critical, damaged data, you shouldn't be running CHKDSK. You should be shutting down your PC, pulling the disk, and sending it off to professional data recovery services before you inadvertently damage the file in a way to make it completely unrecoverable. Or, restoring from a known good backup.

Running CHKDSK isn't going to magically wipe out your video collection.

 

[jaqie]

Mushkins is the first person in this thread that is actually talking sanely and giving good info.

The rest of you, shame on you! Either intentionally spreading FUD or talking out of your behind or parroting things you have read from so-called experts.

 

[corkyg]

Andd this is why all my systems have a pair of duplicate drives, and I rotate them every Wednesday. Been doing it for nearly 20 years and have rarely had to run scan or check disk.

In addition to that, all data is backed up externally. It sort of gives me an Alfred E. Neuman attitude.

An "expert" is a SOB from out of town carrying a clipboard.

 

[KingFatty]

I thought you could run CHKDSK in a read-only mode, just so it could let you know if there were issues, without actually changing anything?

 

[Elixer]

Mushkins is the first person in this thread that is actually talking sanely and giving good info.

The rest of you, shame on you! Either intentionally spreading FUD or talking out of your behind or parroting things you have read from so-called experts.

and just what part in what I wrote is incorrect or FUD ?
http://forums.anandtech.com/showpost.php?p=35290382&postcount=12

 

[GlacierFreeze]

This is pretty much where the guy lost any and all credibility, waiving his self described credentials around like they mean he knows what he's talking about.

OP, you're overreacting.

Agreed. I wouldn't listen to Moulton. He's "too smart" for his own good.

I've "fixed" more computers (only a few) using scandisk than it has ruined for me (zero). And no data loss.

 

[SOFTengCOMPelec]

I've "fixed" more computers (only a few) using scandisk than it has ruined for me (zero). And no data loss.

I've had a lot of data loss (**ONLY WHEN DISKS DATA IS ALREADY CORRUPT IN SOME WAY**), and had the same problem with other people, connected with Chkdsk/Scandisk.

What I have NOT made very clear in my earlier posts, is that if the disk is problem free, Chkdsk/Scandisk is fine, and DOES not corrupt it or anything.

My experiences have included potentially much older versions of windows, than people are using now (they were often latest version of windows at the time).

In general the more modern NTFS filing system, has been considerably more robust and reliable in my experience.

The OP seems to be describing an external HDD, which may have been using FAT or something which was NOT NTFS, he does not detail exactly what he was using.

Mushkins is the first person in this thread that is actually talking sanely and giving good info.

The rest of you, shame on you! Either intentionally spreading FUD or talking out of your behind or parroting things you have read from so-called experts.

Some or all of the posts seem fine to me. I may not 100% agree with everything that every post says.

As regards MY posts, I definitely AGREE that I was "HEATING UP THE FIRE/PANIC/TENSION", rather than being a better AnandTechForumer and relaxing/cooling/de-panicking the situation.
I let the OPs apparent tensions, speedup/cloud my posts too much, and they were not carefully enough constructed.
I should have spent more time, reading the OPs quotes, and commented on their possible inaccuracies, before jumping in like I did.

 

[VirtualLarry]

In the DOS days (and Win9x), I would use SCANDISK, but in read-only mode (no "/FIX"), to find errors after an unsafe shutdown (on FAT32 filesystem).

If there was corruption in the FAT table, I would go in with a disk sector editor and fix it manually. Because that's the kind of guy I used to be back in the DOS days.

 

[fzabkar]

CHKDSK is fine in readonly mode, but potentially data destructive in repair mode. Even FDISK and FIXBOOT can trash your file system under certain circumstances. In fact I personally have come to grief after Microsoft's FIXBOOT turned a 40GB HDD FAT32 file system into a 10MB FAT12 file system (I still cannot understand why an MS programmer would do something so amazingly stupid).

CHKDSK is reasonably safe if the problem is a "logical" one (eg corrupted file system due to unexpected power loss), but dangerous if the problem is "physical" (eg unreadable sectors). Anyone who doubts this can visit the HDD Guru forum.

 

[dave_the_nerd]

Most disk repair utilities take an "And if thy right eye offend thee, pluck it out" approach for corrupted sectors of clusters. Because that's the safest, most reliable way to get a working directory/FAT/MBR/whatever back to the user in the quickest amount of time. Even if you have to throw out the occasional data.

And it's usually a temp file or logfile or something, since 99 times out of 100, when your computer BSODs with a file in use, that's what it's doing (so that's the data that's goofed up.)

I've lost far more data to badly-implemented auto-save functions than I ever have or ever will to disk utilities.

So, yeah, always have a backup.