• Year 0 – I filled 10 32-GB Kingston flash drives with random data.
• Year 1 – Tested drive 1, zero bit rot. Re-wrote drive 1 with the same data.
• Year 2 – Tested drive 2, zero bit rot. Re-tested drive 1, zero bit rot. Re-wrote drives 1-2 with the same data.
• Year 3 – Tested drive 3, zero bit rot. Re-tested drives 1-2, zero bit rot. Re-wrote drives 1-3 with the same data.
• Year 4 – Tested drive 4, zero bit rot. Re-tested drives 1-3, zero bit rot. Re-wrote drives 1-4 with the same data.

Will report back in 2 more years when I test the fifth. Since flash drives are likely to last more than 10 years, the plan has never been “test one new one each year”.

The years where I’ll first touch a new drive (assuming no errors) are: 1, 2, 3, 4, 6, 8, 11, 15, 20, 27

The full test plan:

YEAR 1: read+write  1                           [1s]
YEAR 2: read+write  1, 2                        [1s]
YEAR 3: read+write  1, 2, 3                     [1s]
YEAR 4: read+write  1, 2, 3, 4                  [2s] (every 2nd year)
year 5: read+write  1, 2, 3,
YEAR 6: read+write  1, 2, 3, 4  5               [2s]
year 7: read+write  1, 2, 3,
YEAR 8: read+write  1, 2, 3, 4, 5, 6            [2s]
year 9: read+write  1, 2, 3,
year 10: read+write 1, 2, 3, 4, 5, 6
YEAR 11: read+write 1, 2, 3,         7          [4s]
year 12: read+write 1, 2, 3, 4, 5, 6
year 13: read+write 1, 2, 3
year 14: read+write 1, 2, 3, 4, 5, 6
YEAR 15: read+write 1, 2, 3,         7, 8       [4s]
year 16: read+write 1, 2, 3, 4, 5, 6
year 17: read+write 1, 2, 3
year 18: read+write 1, 2, 3, 4, 5, 6
year 19: read+write 1, 2, 3,         7, 8
YEAR 20: read+write 1, 2, 3, 4, 5, 6       9    [8s]
year 21: read+write 1, 2, 3
year 22: read+write 1, 2, 3, 4, 5, 6
read 23: read+write 1, 2, 3          7, 8
year 24: read+write 1, 2, 3, 4, 5, 6
year 25: read+write 1, 2, 3
year 26: read+write 1, 2, 3, 4, 5, 6
YEAR 27: read+write 1, 2, 3          7, 8,   10 [8s]
year 28: read+write 1, 2, 3, 4, 5, 6       9
year 29+: repeat years 21-28

FAQ: https://blog.za3k.com/usb-flash-longevity-testing-year-2/

Year 0 – I filled 10 32-GB Kingston flash drives with random data.
Year 1 – Tested drive 1, zero bit rot. Re-wrote the drive with the same data.
Year 2 – Re-tested drive 1, zero bit rot. Tested drive 2, zero bit rot. Re-wrote both with the same data.

They have been stored in a box on my shelf, with a 1-month period in a moving van (probably below freezing) this year.

Will report back in 1 more year when I test the third 🙂

FAQs:

• Q: Why didn’t you test more kinds of drives?
  A: Because I don’t have unlimited energy, time and money :). I encourage you to!
• Q: You know you powered the drive by reading it, right?
  A: Yes, that’s why I wrote 10 drives to begin with. We want to see how something works if left unpowered for 1 year, 2 years, etc.
• Q: What drive model is this?
  A: The drive tested was “Kingston Digital DataTraveler SE9 32GB USB 2.0 Flash Drive (DTSE9H/32GBZ)” from Amazon, model DTSE9H/32GBZ, barcode 740617206432, WO# 8463411X001, ID 2364, bl 1933, serial id 206432TWUS008463411X001005. It was not used for anything previously–I bought it just for this test.
• Q: Which flash type is this model?
  A: We don’t know. If you do know, please tell me.
• Q: What data are you testing with?
  A: (Repeatable) randomly generated bits
• Q: What filesystem are you using? / Doesn’t the filesystem do error correction?
  A: I’m writing data directly to the drive using Linux’s block devices.