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Got 2 USB keys from Ebay partitioned as 32GB and 64GB resp. Neither one is unable to accept or hold that much when I attempt to fill them in with data. I suspect they're both overpartitioned. What do I do to "tell" each of them they're smaller capacity ones, e.g. 8GB, in an attempt to guess their true capacity and thereby hopefully fix them? Windows tools and apps would be preferred over Linux ones other things equal.

Many thanks in advance!

dandreye
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    `diskpart clean` will erase the partition table so you can repartition and reformat the drives. https://technet.microsoft.com/en-us/library/bb490893.aspx – bwDraco Dec 22 '16 at 17:52
  • bwDraco: just tried - after diskpart clean the 32GB one I tried first still sees itself as a 30.3GB drive as per Bootice Partition Management details. If I restore partition table saved using a genuine 8GB key earlier and format it, new partition shows up as 7.5GB while entire disk keeps showing 30.3GB (C/H/S = 3951/255/63). Is there any way to make it forget the latter? – dandreye Dec 22 '16 at 21:10
  • That's interesting. Does the drive indeed hold that much data? – bwDraco Dec 22 '16 at 21:32
  • Definitely not (as already mentioned in my initial post). I don't remember exact symptoms of its misbehaviour anymore as I tried filling it with data a long time ago. This minute I'm writing 8GB into it (after partitioning/formatting it to 8GB as you suggested) to see whether it can hold at least that much. – dandreye Dec 22 '16 at 21:37
  • Then the drive is bad. Unless you can somehow reprogram its controller, I'd throw it out or return it to the seller. – bwDraco Dec 22 '16 at 21:39
  • They fully refunded me already back then as these keys weren't holding specified amount of data. I just didn't throw them away and now decided to try if they can hold any amount at all. My 8GB write test has succeeded: wrote 2 big iso files onto it (3.99GB and 3.23GB) and was able to read it back and open w/o any issues. I'll try using them as 8GB ones then: I need them as bootable drives with various popular freeware, so possible data corruption is not an issue at all. Thanks for your help! – dandreye Dec 22 '16 at 22:21
  • Great! If the answer solved your problem, be sure to click on the check mark next to the answer so that we know your question has been successfully resolved. – bwDraco Dec 22 '16 at 22:22
  • Done (I think): clicked on arrow up, 0 changed to 1. – dandreye Dec 22 '16 at 22:25
  • That's an upvote; that indicates the answer is useful but doesn't quite mark the answer as the solution. Click on the check mark itself to accept the answer. See http://superuser.com/help/someone-answers – bwDraco Dec 22 '16 at 22:33
  • Just done it (apologies for the delay). – dandreye Dec 29 '16 at 16:10

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The first thing I'd try is diskpart clean, which erases the drives' partition tables so that they can be repartitioned and reformatted without an erroneous partition table or boot sector. Basically, you run diskpart in an elevated command prompt, select the drive, and issue the clean command. You'll want to see this answer for a more detailed description of this process.

If this doesn't work and the drive continues to claim that it's larger than it really is, then it's bad and needs to be returned or discarded.

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bwDraco
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