[TC 6.03a] Read errors ignored?

[white]

Today I was at my friends house. He had some files on a CD recordable he wanted to copy to his hard disk. One file could not be copied. Using Windows 98 SE Explorer an error message was displayed stating that the file could not be read. Using TC 6.03a the file was copied partly (took longer than normal) and no error was displayed!

Can anyone confirm TC is ignoring read errors?

[Sheepdog]

Can anyone confirm TC is ignoring read errors?

I cannot confirm the ignoring of reading errors. But maybe TC tries a few more times to read the data from CD or even to slow down the drive speed.

On CD is for each block of data a checksum added. While reading the CD-drive checks the data using this checksum. Speeding the drive down could help to recover data as well as repeated reading, because already one weak bit causes a wrong checksum.

I doubt that TC would ignore read errors and copy defective data. You should try to copy these data more than once and after that perform a compare by content. That should produce no errors (apart of a possibly different lenght and resulting differences).

sheepdog

[white]

I doubt that TC would ignore read errors and copy defective data. You should try to copy these data more than once and after that perform a compare by content. That should produce no errors (apart of a possibly different lenght and resulting differences).

TC partly copied the file (length was shorter). I tried several times. Using a CDRewritable device and a CDROM device to read the file. Same results.

Funny thing: I did a "Synchronize dirs" afterwards and compared by content. Only the partly copied file was indicated as being not equal (probably because the length of the file was different). In the results lists of the "Synchronize dirs" window I right clicked the partly copied file and chose "Compare left and right". TC stated the partly copied file was identical to the file on the CD recordable! Again no error was displayed.

[pdavit]

Did by any chance your TC crashed during coping and it didn’t have the chance to clear any data?

In addition, some file types don’t actually have an end-of-file flag (e.g. mpeg movies) and data can be kept up to the located error as partial.

[Sheepdog]

TC partly copied the file (length was shorter).

I remember that I had a similar prob some times ago. TC was copying only a part of the file. But I can not remeber if there was a message or not. So I'm pretty sure that your file on CD is readable to a certain block. Explorer deletes this file while TC saves it. Saving could be sometimes useful e.g. if you have a large textfile and can access at least the readable part.

Funny thing: I did a "Synchronize dirs" afterwards and compared by content. .......Again no error was displayed.

While syncronize TC notices the different size of the file.

While compare by content apparently only the readable part is compared and than compare is breaked ( as copying).
That's the explanation.

But I think TC shouldn't act like this. It's okay to save the partial file but you should get a message that the file isn't completely copied (or compared).

BTW this wasn't exactly what I proposed to do. I meant you to copy the file two (or more) times to different folders to HD and then compare the files on HD by content to check that TC is at least coping this part identical (to prove that he does not ignore reading errors)

Did by any chance your TC crashed during coping and it didn’t have the chance to clear any data?

I bet there isn't any chance:

I tried several times. Using a CDRewritable device and a CDROM device to read the file. Same results.

sheepdog

[white]

So I'm pretty sure that your file on CD is readable to a certain block. Explorer deletes this file while TC saves it.

It seems to me that is exactly the case.
By the way. It concerns a jpg picture from a digital camera. I was able to open the jpg file from the CD in a graphic program. This graphic program also did not display an error message, but seems to read the file up till the unreadable block.

But I think TC shouldn't act like this. It's okay to save the partial file but you should get a message that the file isn't completely copied (or compared).

That is exactly the point is was trying to make. Thanks for making it more clear.

BTW this wasn't exactly what I proposed to do. I meant you to copy the file two (or more) times to different folders to HD and then compare the files on HD by content to check that TC is at least coping this part identical (to prove that he does not ignore reading errors)

There is no doubt in my mind that the copied part is the same as the original. With "ignoring read errors" I meant not displaying a message that the file was not completely copied (or compared).

Did by any chance your TC crashed during coping and it didn’t have the chance to clear any data?

No.

[icfu]

Offtopic
Two nice apps you can try to recover "unreadable" data:
IsoBuster
Roadkil's Unstoppable Copier

Edit:
Link of Roadkil's Unstoppable Copier corrected, thx Sheepdog.

Icfu

[white]

Here are some quotes from private email concerning the subject.
(Published with consent of Christian Ghisler)

I am copying a file from a CD recordable to my harddisk.
Using windows explorer an error message (see below) is displayed and the file is not copied.
Using TC 6.03a the file is partly copied and no error is displayed!
Is this a bug? (the user should be notified the file was only partly copied)

Error message displayed by windows explorer:
Window caption: "Error Copying File"
Message: "Cannot copy <file name>: The system cannot read from the specified device."

This is unfortunately a bug of the Windows API with some CD drivers on Win9x: The windows function does NOT return an error, it returns success although the file isn't completely copied. I have tried to find a workaround with another user, but unfortunately there is no workaround, it's impossible to find out whether the copying worked or not. I have no idea how explorer finds out, perhaps it checks the file size after copying...

To be precise, the ReadFile function returns no error even if it doesn't copy the entire data. Total Commander doesn't rely on the file size reported by the disk so it can copy currently open files (e.g. on CD-RW) where the size changes during copying.

[Sheepdog]

Offtopic
Two nice apps you can try to recover "unreadable" data:
IsoBuster
Roadkil's Unstoppable Copier

Icfu

The website with Roadkil's Unstoppable Copier has changed to
http://www.roadkil.net/

sheepdog