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Out of space on FAT32 pendrive


When I'm copying a file > 4 GB to a FAT32 pendrive, it copies it until it reaches ~4 GB and then says the drive is out of space. This is ridiculous for at least two reasons:

  1. It took me a while to figure out why it says "out of space" when there's still more than 20 GB of free space (simplest solution -- maybe the message could just suggest that the file is too big?)
  2. DOpus could have told me earlier -- at the very beginning of copy operation -- instead of wasting my time waiting for operation that has no chance of finishing

Here's similar topic: There is not enough space on the disk
I understand that it might not be possible to detect max file size on network disks (like in the linked topic) but you can do that on pendrives, is that correct?


The error code and message come from the operating system. We just pass the information through and do not know if the filesystem really did run out of space or if it is just saying it did for another reason.

We could detect if FAT32 is being used and add some extra checks, but it could also make every copy operation slower (which can have a large effect when copying lots of small files), and it would be specific to FAT32 as it's not always possible to know what a filesystem will do.

Avoiding FAT32 is my advice. It is not fit for purpose with modern file sizes. exFAT is much better, although not as widely supported by other devices (but I think that is changing, largely due to the 4GB limit).


Thanks for explaining. I'm not an expert but maybe DOpus could check the filesystem format once and remember it until the device is dismounted or for certain period of time or once per copy job.

Anyway, this is not critical but something you may consider worth improving. Thank you for looking into the matter.


Maybe we could do something. Thinking about it some more, we'd only need to do the check on large files, and the overhead compared to copying that much data is small.

Checking free space in general is difficult to do accurately (and doing it badly is arguably worse than not doing it at all) but we probably could have a warning for files too big for FAT32.


Large amount of data, plus I personally had to copy 4 GB several times before figuring out what's going on. :slight_smile:


You can also add filesystem-info to status bar, so you can see if a drive is fat or ntfs.


For me it's a waste of space on my status bar to have it displayed all the time while I only need this once per week or something. Plus, I probably wouldn't look at it at all anyway. I only bother to check if there's enough space on the disk. :wink:

Anyway, thanks for this tip.


In the next update Opus will show an error immediately if you try to copy a file > 4GB in size to a FAT or FAT32 drive.