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I use a mac and have a zip file that contains a base set of files that I use over and over. Every time I need the set of files for a new project, I simply unzip the zip file and they are ready for use. I have unzipped the same zip file over and over again. I have never received an error or corruption alert, but am wondering if unzipping the same zip file repeatedly will cause any data corruption. Thanks!

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3 Answers

It's unlikely that the act of unzipping a file will cause any kind of corruption since decompression is a read-only process. However, there is a small chance that repeated access to the file over long periods could cause the disk sectors on which it resides to become corrupted, since it is a magnetic medium and is subject to wear. To mitigate that risk, you can periodically copy the file to another storage device, delete it on the original disk, and copy it back to the original disk. This will (most likely) result in the file being written on different sectors.

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Interesting! Thanks! But if we're talking a few dozen times or so Im sure that wouldn't be frequent enough to have to do this. –  Brandon Apr 5 '13 at 3:05
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Cloning your HD to another one every 2 years is good enough to prevent demagnetization. It doesn't really matter if you read the same ZIP one billion times, Windows does that every minute with a thousand of static system files and they don't wipe out. –  Havenard Apr 5 '13 at 3:13
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Keep in mind that there are OS files on the disk that are read literally millions of times more often than that zip file. –  Daniel R Hicks Apr 5 '13 at 11:11
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No, it shouldn't - providing the file doesn't get corrupted in any other way (e.g. filesystem damage).

Related: Can zipping a file break it?

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Thanks Renan! No I havent gotten any other corruption issues. So I can technically unzip the same file hundreds of times without worrying about it? –  Brandon Apr 5 '13 at 2:58
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Yes. Zip files (or other files, for that matter - except if you save as lossy formats like JPEG or MP3, which is not the case here) won't degrade if you reuse them. –  Renan Apr 5 '13 at 2:59
    
Got it! Thanks! –  Brandon Apr 5 '13 at 3:01
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No, it would not, because "Compression software works by using mathematical equations to scan file data and look for repeating patterns. The software then replaces these repeating patterns with smaller pieces of data, or code, that take up less room. Once the compression software has identified a repeating pattern, it replaces that pattern with a smaller code that also shows the locations of the pattern. For example, in a picture, compression software replaces every instance of the color red with a code for red that also indicates everywhere in the picture red occurs." - http://smallbusiness.chron.com/file-compression-decompression-930.html

For decompression, the computer just calculate again an write a temporary file in your Temp folder as in Windows. Therefore the original file is Read Only in this process. But when you put something or take out something from the archive, it can also be done with modern archive managers, like: 7-zip... In this case, you may corrupt a file.

The other chances are: that you experienced a hard-drive damage, sometimes the system used some space in the file to write other files that causes the problem; Or you experienced a virus attack;

It is always an advise for you to backup your files!

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