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USB flash drives not 100% reliable?

M

MDesigner

Platinum Member
I was doing an experiment by copying a 300MB file onto my Kingston USB flash drive..and then duplicating it on the flash drive several times. I noticed in some cases, the CRC of one or more of the duplicates didn't match the original. Is this typical of flash drives? If so, why? Is it the fact that it's a USB storage device? Or the fact that it's non-volatile storage space? Do they make USB flash drives that have built-in CRC/ECC?? I guess I could just copy md5sum onto the flash drive and use it when I copy large files to make sure they copied correctly.. but that's kind of a hassle.
 
Could be a local problem. I regularly use flash media to move large files (13.5 megapixel images) from one machine to another - but that is way out the league of what you are attempting to do.

Based on your experience, I would avoid replicating such humongous files on a thumb drive. It could be circumstantial and possibly USB related. Quien sabe?
 
Yeah.. we're talking large large files here (300MB+). If anyone else would care to test their USB flash drives out:

1) Take a file that's at least 300MB and copy it to the USB flash drive.
2) On the USB flash drive, right click + drag the file and choose "Copy Here" to make a dupe.
3) Compare CRCs. Rinse & repeat (go to step 2). You may need to delete the dupe to free up space.
 
Are you talking about creating a copy of the file on the same flash memory? If so, you have to change the filename, right? That could make for a different CRC. What does it look like opening the files and walking through them? Any apparent difference?
 
Changing filenames does not change the CRC. Nor does a different creation/modification date. CRC is purely based on file contents. And no, viewing/listening to the file is fine.. seems to be the same. It's very odd. Regardless, it's considered a corrupt file. If I RAR up a file, copy it to the flash drive and the CRC has changed, then unpacking the RAR archive will result in a CRC error.
 
Maybe you just got a bum flash drive. I guess you figure with the hundreds of thousands they make, there's bound to be a few oddballs.
 
This should not happen.

Possibilities include faulty RAM in your PC, a faulty USB port, possibly a CPU or motherboard fault (but less likely), or a faulty USB key.

Because flash drives are highly susceptible to corruption due to background radiation (especially if taken on aircraft) all drives include a powerful ECC mechanism, which should make actual data corruption a very rare event. However, this ECC mechanism assumes that the correct information is able to get to the flash drive in the first place.

I'd strongly recommend trying the memory stick in a different PC and seeing what happens.

If it works fine, then you need to look at your PC.

Run memtest86+ overnight and see if there are any errors. If you get any errors at all, it suggests a problem with your RAM - either the RAM is faulty, or it isn't compatible, or there is some sort of problem with the memory subsystem of the motherboard.

You could also try a different model of flash drive and see what happens. If it too doesn't work then it strongly suggests a USB problem with your PC.

Some PCs have 'flaky' USB connections - VIA chipset based motherboards, and some early nForce (nForce and nForce2) boards are particular offenders. If you've got one of these PCs with flaky USB, you could try a PCI USB add-on card (just don't get one with VIA chips on it, because they work just the same).

I had exactly the same problem, except it was with external HDs rather than flash drives - things would randomly get corrupted. It was due the flaky USB of Abit's NF7 mobo. Finally after 12 months of scratching my head about the problem, Abit released a BIOS patch - and everything started working properly.

 
Nope, RAM is fine..already ran a 17 hr test. Here's a thought.. the USB port I'm plugging it into is in the side of my monitor. So.. my monitor has a USB plug that goes into the back of the PC. Could it be that the problem is occurring because I'm not plugging it into a USB port that leads DIRECTLY into the PC? Just a thought..
 
I don't think your problem is issolated. I had a Sandisk Cruzer in which I copies pictures to all the time. In one case I got a picture that was half dark and half light. I think the number or USB drives that have defective RAM is higher than system memory. Most people would never even know their RAM was defective because it only causes problems once in a while and they are tiny problems.

Anyway, what did you use to test your flash drive? I lost mine it seems and I am in the market for a new one. I had system memory that was bad and it caused me trouble for so long. I never even suspected it was the RAM until I ran memtest86. All that time I could have been trouble free if I just had taken 10 minutes to burn a CD and test the memory.
 
Originally posted by: DaveSimmons
Are you being too lazy to "safely remove hardware" before unplugging the drive?
Click to expand...

Dave - that's not laziness - it simply is not necessary unless you have write caching enabled for a removable drive. And, that takes away from the advantage of a hot pluggable device. Going to "Safely Remove Hardware" for flash memory devices is inefficient.
 
Originally posted by: DaveSimmons
^ you're right, I'd thought the default for caching was on, but at least from mine it is off. Yank away 🙂
Click to expand...

I wonder if it is on by default for Windows 2000. Every time I unplug something, the warning box comes up for me to safely remove things next time. That does not happen in Windows XP.
 
Originally posted by: Staples
I wonder if it is on by default for Windows 2000. Every time I unplug something, the warning box comes up for me to safely remove things next time. That does not happen in Windows XP.
Click to expand...

Yes, AFAIK, W2K doesn't have the "Optimize for quick removal" setting that XP does, and by default W2K does write-caching for those drives, necessitating using the "Safe Removal" UI.
 
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