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We have a large zip file (25GB) containing mosty pdfs and png files. (about 150000 files)

When we unzip the file using windows explore some of the content is corrupted. Some png files shows content of other png files, some pdf's won't open. Some are ok.

When we unzip the file using 7zip everything is ok. The zip file was packed on a 2008 server sent over ftp and unpacked on a 2008 server.

Have anybody seen anything like this before and can explain why the explore unpack corrupts the files?

It's very concerning that explore doesn't crash or show an error message if it fails.

Oliver Salzburg
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olve
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2 Answers2

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ZIP files originaly had a 4,294,967,295 byte size limit, back in 1989 when ZIP was first developed that was more than enough, but now that you can store 10 times that on a micro-SD card the size of a babies nail it is incredibly tiny.

ZIP64 increased this size limit to 18,446,744,073,709,551,615 bytes. However Windows Explorer does not support ZIP64 so the maximum size you can get without problems using only explorer would be approx 4GB.

For more information you can see the Wikipedia page for ZIP file formats

Kevin Anthony Oppegaard Rose
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I had trouble opening a 5GB zip file copied acrosss the LAN using XCOPY. It would open OK on the source computer that had WinZip installed (Windows XP x86) but wouldn't open on the destination computer (Server 2003 x64) which only had the native zip support.

After I installed WinZip on the destination PC I could open up the file without any corruption warnings

thommck
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