7-Zip 9.28 alpha

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  • Igor Pavlov

    Igor Pavlov - 2012-06-20

    7-Zip 9.28 alpha was released.

    This is a development version.
    Don't use 7-Zip 9.28 alpha to process important files and archives.
    If you need more stable version, you can use 7-Zip 9.25 alpha.

    7-Zip for 32-bit Windows:


    7-Zip for 64-bit Windows x64:


    What's new after 7-Zip 9.25 alpha:

    - LZMA2 now is default compression method for .7z format.
    - 7-Zip now can update WIM archives.
    - 7-Zip File Manager now can move files to archives.
    - 7-Zip File Manager now can calculate CRC-32, SHA-1 and SHA-256 checksums for files.
    - The default encoding for TAR format now is UTF-8. You can use -mcp=1 switch for OEM encoding.
    - Command line version:
        - new "rn" command to rename files in archive.
        - new -sdel switch to delete files after including to archive.
        - new -sns switch to store NTFS alternate streams (for WIM format only).
        - new -sni switch to store NT security information for files (for WIM format only).
    - Speed optimizations for opening big archives and big disk folders.
    - DMG support was improved
    - Some bugs were fixed.
    - New localization: Aragonese.

    What's new after 7-Zip 9.27 alpha:

    - LZMA2 now is default compression method for .7z format.
    - Some internal changes.

    7-Zip 9.28 alpha version is provided without source code.
    Source code will be released in future beta version.

    Please write here about any new bugs.

  • gora2

    gora2 - 2012-06-20

    - LZMA2 now is default compression method for .7z format.

    The help file, in the description of switch m the default method was LZMA :(

  • adam socha

    adam socha - 2012-06-20

    Please add 7zip icon to context menu.

  • Ungifted

    Ungifted - 2012-06-20

    Still need option for  archive name templates…
    Like "-ag" in rar

  • ZeMarVe

    ZeMarVe - 2012-06-21

    Hello, Igor.

    Thanks for new alpha.

    I expect support for multi volumes zip archives, created with WinZip.
    Volumes have extensions from z?? to zip, where z01 is first part, z02 - second, …., zip - last.

    Do you plan to support it?

  • Richard

    Richard - 2012-06-22

    Well the switch to LZMA2 certainly pegs all my cores at 100% when compressing now (which I've seen very few programs do), but this tells me it's a much better multithreaded algorithm compared to LZMA so I'm impressed.

  • Fallon

    Fallon - 2012-06-23

    With the 7-Zip settings I use with 4GB RAM,
    Rightclick, 'Add to Archive …' has somewhat better compression than 
    Rightclick, 'Add to Filename.7z' 

    Used settings in 7zFM.exe:
    Archive format: 7z
    Compression Level: Ultra
    Compression Method: LZMA2
    Dictionary size: 32MB
    Word size: 128
    Solid Block size: 512MB
    Number of CPU threads: 8

    Windows7 64bit, source two zip files:

    Properties 7-Zip - ('Add to Archive …' with LZMA2)
    Size: 24 872 905
    Packed Size: 24 468 017
    Folders: 0
    Files: 2
    CRC: 93136DC1

    Type: 7z
    Solid: +
    Blocks: 1
    Physical Size: 24 468 229
    Headers Size: 212

    Properties 7-Zip - ('Add to Filename.7z' )
    Size: 24 872 905
    Packed Size: 24 469 569
    Folders: 0
    Files: 2
    CRC: 93136DC1

    Type: 7z
    Solid: +
    Blocks: 1
    Physical Size: 24 469 781
    Headers Size: 212

  • PIK

    PIK - 2012-06-23


    I didn't (quite) follow that.

    Me on 9.26:
    "I think, or mean, its time only for bugfixing and rewrite LZMA2. Firefox12 program dir
    9.26 LZMA (2 threads, ultra, 64MB, 256, 2GB) in ~6.5 seconds
    9.26 LZMA2 (4 threads, ultra, 64MB, 256, 2GB)) in ~7.5 seconds (!)
    (both ~16.4MB)"

    LZMA2 ist slower and need more "tons" of RAM as LZMA.

    "4+ threads multithreading in LZMA2 is useful only for big file sets (4x of dictionary size, more than 256 MB for 64 MB dictionary)."

    9.28 changes:
    "LZMA2 now is default compression method for .7z format."

    Roshal with 4.20:
    He optimize his ancient huffman-loss algo once for multithreading, make bigger the buffers (but only ~120MB more than 4.11) and compress my Fx12 dir to 17.9MB. In 2.5 seconds…

    Question (whereas):
    What are the huge big changes of LZMA2 in 9.28, to can justify make - in 9.26 "useful only for big file sets" - LZMA2 immediately as defautl method?


  • Igor Pavlov

    Igor Pavlov - 2012-06-23

    Try "Normal" instead of "Ultra" and probably you will see the difference.

  • Igor Pavlov

    Igor Pavlov - 2012-06-23

    To get good multithreading in LZMA2 for small data you must use small dictionary size.
    So maybe you must set 4 MB dictionary (as in WinRAR) for Firefox files.

    I suppose that LZMA2 is pretty good to be default method.
    Compression time for small file sets is not too important.
    But for big file sets the difference in time between LZMA and LZMA2 will be big.

  • Joao

    Joao - 2012-06-23

    I would like to request that you add the option \"Wipe Temporary files created by the 7-zip\" in the 7-zip GUI to use SDelete from Microsoft  available freely at technet.microsoftcom/en-us/sysinternals/bb897443.aspx  so that if the user downloads it and puts it in the 7-zip directory it would use it to wipe the temporary files permanently (no matter if are normal or encrypted files)… the user could specified the number of times the wipe would be done (default 3, but could be just 1… our 100, the user choses) … something like this:

    \"C:\\Program Files\7-zip\sdelete.exe\" -p 3 -s -q \"%TEMPS%\"

    Where: %TEMPS%  would be the temporary directory created by the 7-zip program.

    Of course because is a command line it could be use by other programs that support command line requests like Eraser and others. All parameters should be possible to configure. And this would be use instead of the normal delete function… that doesn\'t really wipes the files permanently.

    Best regards

  • Cessas Hems

    Cessas Hems - 2012-06-24

    FYI: Unable to sort files and/or folders by extensions (almost all versions.)!.

  • Anonymous - 2012-06-24

    Please consider www cryptopp com

    "The License of Crypto++ is somewhat unusual amongst open source projects. A distinction is made between the library as a compilation (i.e., collection), which is copyrighted by Wei Dai, and the individual files in it, which are public domain. "

  • Anonymous - 2012-06-24

    Also send a email  to www schneier com , he will inform about current trends…

  • Fallon

    Fallon - 2012-06-25

    > 'To get good multithreading in LZMA2 for small data you must use small dictionary size.'

    and … with small Solid Block Size, 8 MB, decompression speed is not too far from non solid speed. Fast enough to temporarily extract and check small files. For example fonts in an archive with up to 10.000 fonts.

  • Enod Barker

    Enod Barker - 2012-06-26

    I would like to request that you add the option \\\"Wipe Temporary files created by the 7-zip\\\" in the 7-zip GUI to use SDelete from Microsoft available freely at…

    Like most things from Microsoft, Sdelete is neither open source nor freely distributable and the source code isn't available. Read the EULA.txt included with the download. Requiring a closed source program for a feature of an open source one is a bad idea. Secure deletion isn't magic; fortunately there are open source options available (see below).

    Having an option for 7-Zip to securely overwrite temporary files-in some circumstances-is a good idea, though. WinZip versions have had the capability to securely wipe temporary files created when dealing with encrypted files (only) for three years now (v 14). WinRAR has had that ability since the beginning of this year (v4.10). And so on.

    So adding that capability to 7-Zip would really be beneficial. As with those programs, doing it when dealing with encrypted files only should be enough.

    The issue is the added work and integrating open source code for wiping, if available. Or coming up with a unique solution. A few open source options I know of offhand to look at available at Sourceforge here if interested in this request: Bleachbit (GPL 2 & GPL 3, source code both on SVN and direct download), Eraser (GPL 3, source code on SVN only) and Darik's Boot and Nuke (GPL 2 & LGPL, source code from direct download only).

  • Enod Barker

    Enod Barker - 2012-06-26

    A question for Igor about the most recent alphas. On all of the alpha releases since v9.25, you include this disclaimer in the release notes for them in this forum:

    "Don't use 7-Zip 9.28(7/6) alpha to process important files and archives. If you need more stable version, you can use 7-Zip 9.25 alpha."

    Are there known issues with 9.26/7/8 compression or decompression that might cause issues on production machines? For alpha releases of software in general, a disclaimer like this makes sense, of course. But I've rarely seen a disclaimer recommending an earlier alpha software version for "important" or production files.

  • Igor Pavlov

    Igor Pavlov - 2012-06-26

    v9.25's is pretty safe as I suppose.
    There are some big changes in code in latest alpha versions (9.26+).
    That new code was not tested enough.

  • Joao

    Joao - 2012-06-27

    Well, enod, what I want is a place where I can call a third party program to make the wipe part, be it SDelete, Eraser, or any other… since adding their own wiping service seems to take too effort from the developer(s) of 7-zip, adding a command line place to call the delete part of the removing the temporary files seems reasonable and probably not to difficult to perform.

    If the third party Wiping program is open source or not it doesn't make difference for me, as long as it at least prevents the software recovery… and that I'm able to verify, and I have done already that in the past… verifying the source code is something I can't do since I don't understand nothing of that.

    And my ask for a solution, doesn't prevent you from using another program, as long has third party programs can call them.

  • Anonymous - 2012-06-30

    Будет ли добавлена в инсталятор возможность установки открываемых по-умолчанию 7-zip'ом типов файлов? :)

  • Anastasios Tampakis

    7-zip is my main compressor during the last year. Recently I try to create batches (.bat) to compress folder structures in a few 7z files, each with the parameters most appropriate for the files. I can see the command line is a powerful one but I think for ease of use, is it possible to just setup the GUI parameters to what we want the compression to be like and have a button  "command line to clipboard" so to directly extract the switches necessary for the command line instead of typing and searching in the docs for the codes to use? A button may not be even necessary, just a line in the GUI that says "command line switches" that reflect the settings in GUI.
    Another feature I have seen in winRAR and I like it, is the ability to prepare some lengthy archives, start all of them and the program automatically works on an archive at a time; the other archives wait in turn to be compressed. I use ultra compression with many cores and if I try to do that simultaneously with two big archives, the system has a tough time, sometimes crashes. I am in need to compress 1-20GB archives, 4 at a time to form the complete archival set and I want to set up this compress overnight. I resolved to .bat files for this now but I suggest an easier mechanism so to be user friendly and operational without much hassle. Thanks for an excellent utility!

  • Anonymous - 2012-07-07

    Archive bit reset

    Is it possible to include an option to reset archive bit after compression, like in rar or zip ?

  • Anonymous - 2012-07-08

    Please add over 4GB support for SFX, or enable split function for SFX.

  • slavfund

    slavfund - 2012-07-08

    I don't want to create new theme.
    in 9.22b
    If name of file has blank + dot by the end or blank two dots or blank and …
    name .
    name ..
    Command 'Extract to \*' creates folder (name) only and DON'T extract any file into it.


  • a5kgly

    a5kgly - 2012-07-10

    Excuse me,
    When could users get the release version number ?
    Thanks a lot.

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