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bashusb-drive

Test the limit of read/write cycles of a USB flash drive

I read from an wiki article (http://en.wikipedia.org/wiki/NAND_flash#Write_endurance) that says flash storage has a limit of read/write cycles (for NAND flash this limit is about 10K-100K).

My question is: Is it possible to test/find out this limit on my PC in a relatively short time (in a few hours or a few days)?

I wrote a simple script (/dev/sdb is flash disk), but since flash controller will do wear-levelling, I think this script may not work. 

echo "0011223344556677" | xxd -r -p > a.bin

for ((n=0;n<1000000;n++)); do
     dd if=a.bin of=/dev/sdb
done
Solution

  • It may be easier to do something like this to fill the device with random data:

    dd if=/dev/urandom of=/dev/DEVICE bs=1M

    Over and over again until the device fails.

    If you want to check for single bit errors you could do the following:

    1. Fill the disk with zeroes - dd if=/dev/zero of=/dev/DEVICE bs=1M
    2. Get the SHA-1 sum of the whole disk - dd if=/dev/DEVICE | sha1sum
    3. Fill the disk with random data - dd if=/dev/urandom of=/dev/DEVICE bs=1M
    4. Repeat until the number from step 2 changes or the disk stops working

    That should probably be wrapped up in a bash script to save you some time.

    NOTE: I used /dev/DEVICE so nobody would accidentally copy and paste these snippets without thinking. You'll need to change it to your specific device and be very careful that you get it right!