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Free up drive space without losing content
Authored by: dbs on Jun 05, '06 09:57:28AM

This should work very well for applications that consist of large numbers of small files, but poorly for continuous tone images or movies. An easy way to judge the potential savings is to just zip an application and see how much smaller it gets.

Since all files are made in 4kB chunks on HFS plus, the more files you have the more wasted space may be hanging off them. (I.e., a file that is 4.2kB of data will be 8kB on disk, resulting in 3.8kB of wasted space.) Compression will merge that space together. However, if the majority of the space is in non-compressible data (binary code, images, etc.) then the overall savings will be small.

For example: iCal has more than 3000 files inside the .app bundle. Uncompressed it is 27.3MB, compressed it is 8.2MB.

iPhoto has more than 13,000 files inside its bundle (!) and is 159MB uncompressed and 98MB compressed.

So the results will vary. (Of course simply removing all the localizations would probably have similar results.)

However I would be reluctant to do this for either iPhoto or iCal as they won't get updated with system updates. Doing this for the dozens of shareware applications I have would work very well, though!



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Free up drive space without losing content
Authored by: pub3abn on Jun 05, '06 12:28:21PM
However, if the majority of the space is in non-compressible data (binary code, images, etc.) then the overall savings will be small.

This sentence could be interpretted to imply that binary code and images are not compressible, but that is not true at all. PRE-COMPRESSED images formats, like JPEG or GIF, do not compress well. But others compress very nicely. Unfortunately some formats like TIFF may be either compressed or uncompressed depending on the file options used, so it is hard to tell without trying.

Binary application files compress quite well on average, which is precisely why even single-file applications are smaller when zipped.

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