[ale] How to stress test flash memory

[Chris Fowler]

On Sat, 2010-11-27 at 12:17 -0600, Richard Bronosky wrote:
> I just bought a cheap CF card from the clearance isle at the PX. I'd
> lke to test the thing for "bad sectors" before I put it to use. I only
> have access to Mac and Linux. I could script something in bash, but I
> figure there has to be a trusted tool for this. Please advise.
> 


I know of no tool in Linux but I've seen one in Windows.

I would simply script it.

Here is how I did it.

a)  Create a bunch of 100M files in /tmp
  dd if=/dev/random of=testfile.01

b)  Create a md5sum file of the files you created
  md5sum testfile.* > testfile-md5.md5

c) Mount stick and copy
 cp /tmp/testfile.* /media/stick

d) umount stick
 umount /media/stick

e) Mount stick and test
  cd /media/stick
  md5sum < /tmp/testfile-md5.md5

If you see all OK then stick is good.  

I've used this process to identify counterfeit memory sticks.

I've ran into counterfeits where I could dd if=/dev/zero the stick and
then fdisk will see the real size but recently I've ran into sticks
where fdisk still saw the fake size.  In the latter case we've tossed
the sticks in the trash.

Good luck.