4 ms·

The issue is that if you exceed the (invisible) limit, you start overwriting the existing data. That's Bad (TM), since there's no indication that it's happening

The issue is that if you exceed the (invisible) limit, you start overwriting the existing data. That's Bad (TM), since there's no indication that it's happening, until you attempt to retrieve the data and discover it's corrupted.

axiolite 2y ago
The subject of this topic, f3, will quickly probe the drive, determine the true size, and create a partition on it of the actual usable size. Using that partition, you will never lose any data. If you try to create a partition in the rest of the drive, it will be immediately corrupted, no tools will show it as good, you won't ever be able to get around to putting data on it to lose it.
- dspillett 2y ago
  > will quickly probe the drive Some scam SSDs are smaller drives with hacked controller firmware that is bright enough to avoid detection with quick scans - you have to write beyond the real capacity then re-read to confirm corruption.
  - axiolite 2y ago
    Have you found cases where "f3probe --destructive" didn't work for you?
    - dspillett 2y ago
      Not first hand, though I've used tools of similar intent and found the quick heuristics, while usually very good, not 100% reliable, and for storage I want to be sure not almost certain. Note that I was warning about quick tests, I'll have to try “f3probe --destructive” on something next time I have some playtime to see whether I'd consider that quick! Of course, it could be much quicker than the full capacity write some tools use to find a defective or deceptive drive¹² but quicker and quick aren't the same. If a quick test says the drive is fake then it is, and many fakes can be detected these ways, but it takes more to convincingly state a drive isn't fake. -- [1] Only a little over true capacity should be needed for that, in the case where writes to anywhere up to capacity will work (which is common as creating a filesystem more complex than FAT/exFat often requires activity similar to what quick write/read heuristics do).
- duskwuff 2y ago
  > Using that partition, you will never lose any data. ... unless/until the underlying flash fails. Which it probably will; there's every reason to expect these drives are made with the cheapest, worst flash available.

axiolite 2y ago

The subject of this topic, f3, will quickly probe the drive, determine the true size, and create a partition on it of the actual usable size. Using that partition, you will never lose any data. If you try to create a partition in the rest of the drive, it will be immediately corrupted, no tools will show it as good, you won't ever be able to get around to putting data on it to lose it.

dspillett 2y ago
> will quickly probe the drive Some scam SSDs are smaller drives with hacked controller firmware that is bright enough to avoid detection with quick scans - you have to write beyond the real capacity then re-read to confirm corruption.
- axiolite 2y ago
  Have you found cases where "f3probe --destructive" didn't work for you?
  - dspillett 2y ago
    Not first hand, though I've used tools of similar intent and found the quick heuristics, while usually very good, not 100% reliable, and for storage I want to be sure not almost certain. Note that I was warning about quick tests, I'll have to try “f3probe --destructive” on something next time I have some playtime to see whether I'd consider that quick! Of course, it could be much quicker than the full capacity write some tools use to find a defective or deceptive drive¹² but quicker and quick aren't the same. If a quick test says the drive is fake then it is, and many fakes can be detected these ways, but it takes more to convincingly state a drive isn't fake. -- [1] Only a little over true capacity should be needed for that, in the case where writes to anywhere up to capacity will work (which is common as creating a filesystem more complex than FAT/exFat often requires activity similar to what quick write/read heuristics do).
duskwuff 2y ago
> Using that partition, you will never lose any data. ... unless/until the underlying flash fails. Which it probably will; there's every reason to expect these drives are made with the cheapest, worst flash available.