Four Compression And Archiving Solutions Compared

7-Zip 9.1 Beta And FreeArc 0.60

7-Zip 9.1 Beta

7-Zip is an open source file archiving tool available at 7-zip.org. It supports a variety of formats that can be unpacked and a limited number of archiving formats. 7-Zip’s Web site claims that the program compresses 2% to 10% better into ZIP format than competing software. This refers to the program’s compression ratio compared to six of its ZIP-based peers.

However, the real strength of 7-Zip is its own 7z format. This open architecture allows the 256-bit AES encryption we tried in our AES-NI Performance Analyzed article, which looked at the performance advantages of Intel’s new Clarkdale-based Core i5 processors when utilizing the six new instructions for AES encryption and decryption. AES is supported within the 7z and ZIP formats. With 7z, you might not see much performance benefit, despite the new instructions. This is because the 7z algorithm is already pretty heavy, slowing down the process enough to make AES acceleration less relevant. This is something we've discussed with Intel, and representatives at the company confirm our findings.

7-Zip isn’t as prolific as some of the other tools in this story, but it’s still supported by other archiving utilities, such as IZArc, PowerArchiver, TUGZip, and WinRAR. Typically, 7-Zip utilizes LZMA compression (LZ77), but it’s also possible to utilize others. LZMA can run variable dictionary sizes of up to 4GB (via a 64-bit OS).

The 7-Zip 9.1 beta also supports the more advanced LZMA2. 7-Zip runs on the command line, or you can use the default Windows GUI that includes a file manager interface. As many as 74 localized language versions are available, and the program runs on all Windows versions from Windows 98 to Windows 7. Unlike WinZip, 7-Zip is fully thread-optimized and can take advantage of multiple processing cores.

FreeArc 0.60

The fast (yet efficient) FreeArc tool is available at freearc.org. The site says that the utility can work up to 3x faster than the best compression programs. This probably refers to WinZip and other popular products. FreeArc runs on either a command line or a GUI, and the list of advantages on FreeArc’s site is impressive. The program is capable of switching between various compression algorithms according to file type. While this helps to maximize the compression ratio, it also binds the user to FreeArc, as other solutions are unlikely to be able to understand and decompress your archives. A total of 11 algorithms are supported. Keep in mind that this doesn’t necessarily apply to compressing--only reading and unpacking archives. It’s also possible to integrate external programs to compress or filter data.

Within a range of up to 1GB, the program can find repetitions (REP), remove repetitions in texts (LZP), and pre-process executables (BCJ). FreeArc also sorts files in an a way that takes maximum advantage of these features. Fast compression settings will automatically use GRZIP for text and Tornado for binary data.

FreeArc can also add encryption to secure your file archives. It supports AES, Blowfish, Twofish, and Serpent. Self-extracting archives, joining, recompressing, locking, and comments are all supported. However, not all file attributes are stored. So far, there hasn’t been a 64-bit version of FreeArc released, and it still lacks support for multi-volume archives. Fortunately, self-extracting archives and the ability to create simple installers are included.

FreeArc is suitable for anyone who doesn’t mind spending a bit of time adjusting archiving solutions for her or his environment. Version 0.7, which should be available around the time this article goes online, is supposed to make “the program as easy to use as WinRAR.” The developers want to add full support for RAR and 7z formats later on.