File size on HD is larger than it should be

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File size on HD is larger than it should be

Hi everyone and thanks in advance for your help!

I have a MBP running Mac OS X 10.7.5. I downloaded a .iso file. The site which I downloaded the file from says the file is 4.31GB, which should fit on a regular single layer DVD-R, which, afaik, can store up to 4.37GB. My torrent client says the file is 4.3GB. However, when I "get info" for the file, it says that it's 4.63GB on disk. When I try to burn on a single layer DVD-R, my MBP says I need a larger DVD-R.

Why is the file size larger on my HD than it should?

Same thing happens with .avi files. I have downloaded several .avi files that are around 700MB in size, but my HD views them around 740MB instead, which renders them unburnable on a regular CD-R.

Any help?

Thanks!

MacBook Pro, Mac OS X (10.7.4)

Posted on Nov 22, 2012 7:06 PM

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Answer 1

LousyFool

Level 4

2,662 points

Nov 22, 2012 7:58 PM in response to Narcisse2

http://www.differencebetween.net/technology/difference-between-size-vs-size-on-d isk/

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Answer 2

Narcisse2 Author

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Nov 22, 2012 8:02 PM in response to LousyFool

This link is informative, but doesn't seem to address my issue. I understand the difference between size on disk and actual size, but it shouldn't refrain me from burning files to a DVD-R or CD-R, should it?

If I download a 10MB file on my HD, I understand that it will appear as, say, 15MB on the HD. But shouldn't it be burned on the MB basis?

Btw, this problem has only started a few weeks ago.

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Answer 3

LousyFool

Level 4

2,662 points

Nov 22, 2012 8:10 PM in response to Narcisse2

First, and you can read and study more about it all across the web, file size on disk depends on file system and cluster size on the disk or media. So, this applies to optical media as well.

Then, I can't imagine how it could have gotten significantly worse within days, weeks, or even longer - unless you reformatted your HD and are since using a different file system, which I doubt you did. Disk fragmentation can add to it over time, but OS X is known to manage this quite nicely.

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Answer 4

Narcisse2 Author

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Nov 22, 2012 10:29 PM in response to LousyFool

I dont understand it either. All I know is that a few weeks ago I remember burning DVD-Rs and CD-Rs without encountering any problem.

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