2014. július 28., hétfő

NTFS compression vs. 7zip

I was migrating 7 years of accumulated "My Documents" (word, PDF, scanned, totally mixed) of my wife to her new SSD, where capacity is still much more scarce.
I took time to decide: shall I compress all unused and old data with 7zip* to save space, but make it a lot more complicated to access them**, or shall I just let NTFS in Windows 7 do the job, leaving them accessible as single files?

I am posting the results, because they differ significantly from what I have expected: that would have been a slightly less efficient compression from NTFS.

Instead, this is what I got (for a subset of "My Documents" M-Z, 67 folders, 1 142 files).

Windows 7 NTFS compression (bytes):
Total size: 1 060 762 801, Compressed: 971 467 130, Gain: 8.4%
7zip Ultra compression (bytes):
Total size: 1 060 762 801, Compressed: 489 906 124, Gain: 53.8%

This means, that NTFS compression was basically useless on her "My Documents" contents, and that is not because the contents were incompressible: 7zip freed up more than six times more than NTFS, giving back more than half of the valuable SSD capacity!

Have had a quick Google: it seems there is no way to beef up NTFS compression levels the way Linux can be tweaked.

Comments Welcome!

*: 7z format, Ultra compression level, which obviously does combine multiple files for better compression, since I was unable to obtain single file statistics.

**: The other disadvantage being that a single archive is most probably a lot more fragile, a bit of damage could potentially make a lot of files inaccessible. Fortunately I have a backup of all the files, so this is not a concern. :)

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