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I just compressed 11.6GB of data on my hard drive into a 4GB zip file using Windows XP Compressed Folders, and deleted the original data. I then found that the 4GB zip file is corrupt. Is this simply because it is too large for Windows to handle correctly? this has never happened to me before.

I was alerted to the issue when I tried to copy the zip file from my hard drive (NTFS) to an empty 16GB memory stick (FAT32) - it said that the empty drive was full.

I would like to understand whether this is just a random occurrence, or some fundamental limit. That will drive my choice of how I recover the data.

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FAT32 has a file size limit of 4,294,967,295 bytes. –  David Schwartz Nov 14 '12 at 8:04
    
The critical thing appears to be that standard zip files themselves have a 4GB limit. I did not notice Windows making any complaint about exceeding this limit. The original file was created on an NTFS system. I only realised the issue when I tried to copy to a FAT32 drive. Otherwise, the FAT32 connection is a red-herring - I still have a corrupt zip file on an NTFS system. –  omatai Nov 17 '12 at 2:21

1 Answer 1

It's not a random event. The FAT32 file system has an almost 4 GB (4 × 10243) file size limit vs NTFS where it is almost 16 EB (16 × 10246). Microsoft released something called the exFAT file system with Vista SP1 designed especially for flash drives, but with a file size limit of almost the same as NTFS's. You can download an ExFAT driver update for Windows XP from here.

After it's installed on your computer you'll be able to reformat your memory stick to be that format and copy files larger the 4 GB to it. Note that only XP systems with the driver installed will be able to access the contents of the memory stick after you reformat it.

Alternatively, you could just reformat your memory stick to be NTFS, but again, that might not be compatible with everything that you want to plug it into and the NTFS file structure has more overhead than exFAT does.

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I'm not convinced. The 4GB file is on NTFS, and is corrupt. Should the mere fact of trying to copy it to a FAT32 partition corrupt it? That sounds unlikely. –  omatai Nov 14 '12 at 23:19
    
No, copying the file should not have corrupted it. There could be a bug or file size limitation in whatever you used to create the .zip file. The maximum size for both a zip archive itself and the individual files inside it is 4,294,967,295 bytes (2**32−1 bytes, or 4 GB) for the standard file format. Anyway, I've heard of utilities that can read and recover at least some of the contents of a corrupt zip archive, perhaps you can get some or most of your data back using one of them. –  martineau Nov 15 '12 at 1:45
    
OK - I was not aware of the 4GB limit for a zip file... and Windows gave me no warning about exceeding it. So far I have not been able to recover a valid archive using Diskinternals Zip Repair - I'll try some other tools, because Zip Repair at least thinks it can recover 6000 or so files, but just does not create a valid zip file at the end of the process. –  omatai Nov 17 '12 at 2:19
    
Your best bet would probably be to try to find something that will allow you to extract as many files from the corrupt file as possible since there's no way to "repair" it if it has exceeded the capabilities of the format. This sounds promising. –  martineau Nov 17 '12 at 2:39
    
Here's another with a free trial. –  martineau Nov 17 '12 at 3:04

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