7-zip compression settings guide
- 1. 7-zip Compression Settings Guide Digital Studio 7 This guide is created to help 7-zip users understand what settings do what and how to achieve best compression on their systems, for this guide I am using 7-zip gui however I believe reading this guide will help you with commend line version as well. For this guide I am using 7-zip version 9.32 Lets Begine:
- 2. 1) Archive Format: From this option you can select what archive format you want to use, however because this guide is dedicated to 7z lets stick to it. although I recommend you take a look at this article Best File Compression Method article. 2) Compression Level: This are presets for the settings, the names are pretty self explanatory, the presets start from Store (This preset compression settings can not be edited because it does not compress files) to Ultra (ultra is the highest compression preset, but we can achieve better compression by manually editing settings) Take a look at this table to understand better (source) Value Description Store No compression is used, files are just stored in archive in its original size. Fast Fast compression. Normal Recommended level of compression. Maximum Better compression, but it is slower and needs more memory. Ultra Best compression, but it is even slower and needs even more memory. 3) Compression Method: Here You can select the compression method, I recommend using lzma2 because it is considered generally as the best compression method, It is always good idea to default to it. Take a look at this for more information (source) Method Description LZMA Default compression method of 7z format. It provides high compression ratio and very fast decompression. LZMA2 LZMA-based compression method. It provides better multithreading support than LZMA. But compression ratio can be worse in some cases. For best
- 3. compression ratio with LZMA2 use 1 or 2 CPU threads. If you use LZMA2 with more than 2 threads, 7-zip splits data to chunks and compresses these chunks independently (2 threads per each chunk). PPMd Dmitry Shkarin's PPMdH algorithm with small changes. Usually it provides high compression ratio and high speed for text files. BZip2 Standard compression method based on BWT algorithm. Usually it provides high speed and pretty good compression ratio for text files. Deflate Standard compression method of ZIP and GZip formats. Compression ratio is not too high. But it provides pretty fast compressing and decompressing. Deflate method supports only 32 KB dictionary. Deflate64 Modified version of Deflate algorithm with bigger dictionary (64KB). More information about compression cooperation see the below table (source) Compressed file size in bytes gzip bzip2 lzma lzma -e xz xz -e lz4 lzop 1 124875819 (120M) 93997047 (90M) 85618192 (82M) 72042179 (69M) 85630688 (82M) 72069084 (69M) 165844264 (159M) 168012430 (161M) 2 119040249 (114M) 87741348 (84M) 81480824 (78M) 70264395 (68M) 81492504 (78M) 70282944 (68M) 165844264 (159M) 166987891 (160M) 3 114931686 (110M) 84816957 (81MB) 79575087 (76MB) 69015118 (66MB) 79586568 (76MB) 69029204 (66MB) 165844264 (159M) 166987891 (160M) 5 102328357 (98M) 81837328 (79M) 69557610 (67M) 67879362 (65M) 69583428 (67M) 67875988 (65M) - 166987891 (160M)
- 4. gzip bzip2 lzma lzma -e xz xz -e lz4 lzop 7 100128597 (96M) 80197758 (77M) 67276420 (65M) 66868212 (64M) 67294092 (65M) 66852780 (64M) - 116205578 (111M) 9 99740486 (96M) 78963640 (76M) 65841213 (63M) 65362226 (63M) 65859432 (63M) 65372696 (63M) - 114824102 (110M) gzip bzip2 lzma lzma -e xz xz -e lz4 lzop 4) Dictionary Size: This is very important parameter bigger dictionary size equals better compression however here are couple of things to look out for: 1) Dictionary Size value difference: I noticed there is a cutoff point, where after some amount of dictionary size you will not get a big compression size difference; for example between 4MB and 128 MB dictionary size there might be a huge compressed file size difference but between 128 MB and 512 there might be only Couple of MB 2) Speed: The bigger the dictionary size is the longer it will take your PC to compress files. 3) System: This is very important you should take in consideration on what pc you are compressing files and on what system you are going to decompress files. Why? the bigger your dictionary size is more Memory(RAM) is required to complete compression and decompression. When you change the value of Dictionary Size make sure that you will take a look at: Memory usage for Compressing and Memory Usage for Decompressing
- 5. Memory usage for Compressing: Make Sure that you have more Memory(RAM) than it is tallying you that it will use. otherwise your pc will most probably hang and require reboo. Memory Usage for Decompressing: Make sure that on a pc you are planning on decompress this file has more Memory(RAM) than it is asking for 5) Word Size: Higher the value the better compression you are generally going to get ( however it is really dependent on files you are trying to compress) You might get really big difference or might get nonexistent difference. You should keep in mind that Word Size, might almost have no effect the size of a compressed file however it will always effect the speed of the compression so sticking to 64 is good practice
- 6. 6) Solid Block Size: With this option you can enable solid compression, which can improve compression when storing multiple similar files. However extracting or adding a single file from an archive like this will take longer than none solid block compression. However the best practice is manually select the size of a block, for example if you are trying to compress 5 files and each file is 512 MB you might select block size 512MB. Block size is up to you and your judgement or easy way out is, just stick with the preset that 7zip is offering you like 2 GB or 4 GB for more information you can see this 7) Number of CPU threads: Select the number of your pc threads that 7z will use, more threads will equal to faster compression, however some people say that, selecting more then 2 threads might hurt the compression size. 8) Split to volumes: This will just split the archive at a special size you specified, for example if you are trying to burn 2 GB of files on a CD you can tell 7z to split the archive every 650Mb, What it will do is create couple of parts, Singe part will not be more than you specified (in our situation 650MB) however uncompromising the files will require all the parts. 9) Update mode: This is where you can select update method Take a look at this for more information (source) Value Meaning Add and replace files Add all specified files to the archive. Update and add files Update older files in the archive and add files that are new to the archive. Freshen existing files Update specified files in the archive that are older than the selected disk files. Synchronize files Replace specified files only if added files are newer. Always add those files, which are not present in the archive. Delete from archive those files, which are not present on the disk.
- 7. 10)Create SFX archive: This will Create a Self-extracting archive you might know what this is, You might have download a file from internet that has a 7z log and when you doable click on it, a window appears and asks you where to extract this files. If you check SFX you are going to create a file that will just do that Self-extracting archive. 11) Compress shared files: This option compress a file when it is open in another application. 12) Enter Password: If you enter password here the archive you are going to create will be password protected by the password you entered. 13) Reenter password: * //Guess what to do here 14)Show Password: This will make viable the password you are entering abow 15) Encryption method: Here you select the encryption method for more information you can take a look at this guide 16)Encrypt file names: Here you can enable or disable archive encryption. 17)Parameters: The Parameters field is for specifying any options you need that are not available via dedicated dialog controls. for more information you can take a look here ________________________________________________________ Used information: Thank you awesome people who worked on them. http://digitalstudio7.blogspot.com/2013/03/best-file-compression-method.html?q=rar
- 8. http://www.altap.cz/salamander/help/7zip/dlgboxes_newarc/ http://sevenzip.sourceforge.jp/chm/fm/plugins/7-zip/add.htm http://pokecraft.first- world.info/wiki/Quick_Benchmark:_Gzip_vs_Bzip2_vs_LZMA_vs_XZ_vs_LZ4_vs_LZO http://peazip.sourceforge.net/what-is-solid-compression.html http://www.ncl.ac.uk/itservice/security/encryption/encryptionprocedures/How%20to%20encrypt %20and%20decrypt%20files%20with%207Zip%20-%20v1.2.pdf http://7zsfx.info/en/ ________________________________________________________ This guide version 0.76 Contact information: Studio76@mail.com Thank you for your time