Posted by: Diabolic Preacher | February 9, 2008

make best use of your disk space archiving files with 7-zip

Although I’d mentioned about 7-zip in my post about my portable applications, what’s really its superb USP is that it now uses LZMA algorithm by default which is an improved and optimized version of LZ77 algorithm. I came across LZMA first on the 5.8 series of Vector Linux which supports .tlz packages (‘l’ to denote the LZMA compression used) besides the usual slackware .tgz packages. Here’s a sort of rough comparisons.

The default .7z format download for Inkscape 0.45 for win32 is 24.3 mb. This file was released on 20th march 2007. Unpacking this archive creates a folder with contents adding up to 155 mb.
When I re-archived this folder using the latest 7-zip version (4.57), the new archive was 19.9mb! further smaller in size.

Its noted that compression rates for zip format varies across programs, so first I tested archiving the 155mb inkscape folder with winrar, choosing to create a zip archive and the archive came to be 45.7mb while archiving the inkscape folder with 7-zip, choosing zip as the archive format resulted in a 43.0mb. zip mein bhi maar kha gaya 7-zip ke saamne.

LZMA features:

  • Compression speed: 500 KB/s on 1 GHz CPU
  • Decompression speed:
    • 8-12 MB/s on 1 GHz Intel Pentium 3 or AMD Athlon.
    • 500-1000 KB/s on 100 MHz ARM, MIPS, PowerPC or other simple RISC CPU.
  • Small memory requirements for decompression: 8-32 KB + DictionarySize
  • Small code size for decompression: 2-8 KB (depending on speed optimizations)

The LZMA decoder uses only CPU integer instructions and can be implemented for any modern 32-bit CPU (or, on a 16-bit CPU with some conditions).

Stuff like portable apps and 7-zip not having equivalents (the way firefox, gimp, openoffice have) in linux, makes it so unfairly difficult to leave windows, but still all hail the opensource software, no matter which platform.
Note, there is a command-line utility p7zip-full in ubuntu/kubuntu repos, but the GUI built for the windows version is a good job done.

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