I have a USB flash drive. After using it for a year or so some blocks became unreadable. I formatted the drive in order these blocks to be marked as bad ones:
Was they really marked and excluded from File Allocation Table? I need to know if I can recommend this approach to non-experienced users who asks me from time to time about their troubles.
How can I get to know now
- if any of bad blocks was found?
- how much bad blocks are
there? - where are they located?
Update1: I want to get to know if standard format procedure can help in such a situations.
Update2: I got to know that bad blocks exist in this drive using ChkFlsh
Error at address 1DF448000h: expected "10101010", found "11110000".
Error at address 1DF544000h: expected "10101010", found "11100100".
Error at address 1DF640000h: expected "10101010", found "00001110".
Error at address 1DF73C000h: expected "10101010", found "11101111".
Error at address 1DF838000h: expected "10101010", found "00000000".
Error at address 1DF934000h: expected "10101010", found "11101001".
Error at address 1DFA30000h: expected "10101010", found "01101100".
Error at address 1DFB2C000h: expected "10101010", found "01000100".
Error at address 1DFC28000h: expected "10101010", found "10100111".
Error at address 1DFD24000h: expected "10101010", found "11010110".
Error at address 00000000h: expected "01010101", found "01001100".
Error at range [000FC000h..001F8000h]: device read error.
Error at address 001F8000h: expected "01010101", found "00110011".
Error at address 002F4000h: expected "01010101", found "00001110".
Error at address 003F0000h: expected "01010101", found "00001110".
Pass #1 completed, 16 errors found.
Test completed, total 16 errors found.
Best Answer
As far as I know, the microcontroller on the USB stick will substitute bad sectors with reserve sectors so that the computer won't see the defect. If the stick runs out of reserve sectors, meaning many sectors went bad, you should see the number of bad sectors if you run chkdsk at DOS prompt.