MD5 Digest - Verification Errors

[JKilroy]

I'm using Express 7.6.111 and am receiving numerous errors of the following type:

 

Generated MD5 digest for file "d:\music\data\someaudiofile.mp3" does not match stored MD5 digest.

 

With a new backup set I get over a thousand such errors. I am backing up over half a million files and the resulting set is over 450GB in size.

 

Repeating the backup operation reduces gradually the number of reported errors. However, even after several dozen repetitions I still get many verification errors.

 

There are no disk or filesystem errors, on either disk (source or destination), according to chckdsk

 

The backup set is stored on a brand new internal WD Caviar SATA drive. I get the same errors when using a WD MyBook Pro external Firewire drive instead.

 

I get the error whether or not I use compression.

 

The errors are definitely not associated with files that may have been changed between opening and verifying.

 

I am at my wits end and am really considering using a different product. Please help.

 

 

 

[Mayoff]

The files are not being copied correctly. You probably have a device communication problem. Try a different sata cable. Try running a disk check on the drives involved. Try to disable software running in the background.

[JKilroy]

Hi,

As I said before, I have run chkdsk and it shows no problems.

 

Both the internal drive and the MyBook Pro pass HD Tune and Western Digital drive testing program tests (this includes a cable check). There is no problem with either disk - as you would expect seeing as both are brand new drives.

 

Anti Virus (AVG) is disabled - still I get errors.

 

I have disabled all startup programs and non-essential services, still the errors appear.

 

What other sort of background program do you suggest might be an issue for retrospect. I really can see nothing that fits the bill?

 

thanks,

[MrPete]

JKilroy, if you've still not found the problem...

 

Data transfer errors can be VERY hard to nail down. Here's a strategy I've found useful:

 

- Create a VERY big file on one drive. One example: an entire partition, say 20GB.

- Copy to the other drive, ideally to 2-3 drives, 2-3 times. Yes, this could take hours.

- Use a tool like TreeComp to compare the copies -- compare at a binary level!

 

I have found that such simple techniques will, on some systems, generate the occasional bit error. Then comes the fun of discovering the culprit.

 

Here are just a few examples:

- flaky RAM memory (use MemTest86+)

- marginal cables, power supply, drive controller, cpu fan, case fan (might only get error when other things are happening, or the room is hot/cold, or whatever)

- marginal hard drive (use SmartMon Tools, specifically smartctl, to run long form internal drive tests)

- buggy BIOS firmware, flaky motherboard, etc

 

Bottom line: discover whether you can really trust your computer to work correctly. Flaky data transfers are a more common problem than many people imagine.