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[Lzip-bug] Tarlz 0.14 released

From: Antonio Diaz Diaz
Subject: [Lzip-bug] Tarlz 0.14 released
Date: Thu, 14 Mar 2019 19:01:37 +0100
User-agent: Mozilla/5.0 (X11; U; Linux i586; en-US; rv: Gecko/20110420 SeaMonkey/2.0.14

I am pleased to announce the release of tarlz 0.14.

Tarlz is a massively parallel (multi-threaded) combined implementation of the tar archiver and the lzip compressor. Tarlz creates, lists and extracts archives in a simplified posix pax format compressed with lzip, keeping the alignment between tar members and lzip members. This method adds an indexed lzip layer on top of the tar archive, making it possible to decode the archive safely in parallel. The resulting multimember tar.lz archive is fully backward compatible with standard tar tools like GNU tar, which treat it like any other tar.lz archive. Tarlz can append files to the end of such compressed archives.

Tarlz can create tar archives with five levels of compression granularity; per file, per block (default), per directory, appendable solid, and solid.

Of course, compressing each file (or each directory) individually can't achieve a compression ratio as high as compressing solidly the whole tar archive, but it has the following advantages:

   * The resulting multimember tar.lz archive can be decompressed in
     parallel, multiplying the decompression speed.

   * New members can be appended to the archive (by removing the EOF
     member) just like to an uncompressed tar archive.

   * It is a safe posix-style backup format. In case of corruption,
     tarlz can extract all the undamaged members from the tar.lz
     archive, skipping over the damaged members, just like the standard
     (uncompressed) tar. Moreover, the option '--keep-damaged' can be
     used to recover as much data as possible from each damaged member,
     and lziprecover can be used to recover some of the damaged members.

   * A multimember tar.lz archive is usually smaller than the
     corresponding solidly compressed tar.gz archive, except when
     individually compressing files smaller than about 32 KiB.

Note that the posix pax format has a serious flaw. The metadata stored in pax extended records are not protected by any kind of check sequence. Because of this, tarlz protects the extended records with a CRC in a way compatible with standard tar tools.

The homepage is at http://www.nongnu.org/lzip/tarlz.html

An online manual for tarlz can be found at http://www.nongnu.org/lzip/manual/tarlz_manual.html

The sources can be downloaded from

The sha256sum is:
999aa051ecff741d1f7d4c136da3f175d5a30dec88b379cef8654682e5472459 tarlz-0.14.tar.lz

Changes in version 0.14:

* The new option '--exclude', which excludes files matching a shell pattern, has been added.

* The new option '-h, --dereference', which instructs tarlz to follow symbolic links during archive creation, appending or comparison, has been added.
(The short option name '-h' no longer means '--help').

* Concatenation and appending to uncompressed archives and to standard output have been implemented.

* The new option '--out-slots', setting the number of output packets buffered per worker thread during multi-threaded creation and appending to compressed archives, has been added. Increasing the number of packets may increase compression speed if the files being archived are larger than 64 MiB compressed, but requires more memory.

Please send bug reports and suggestions to address@hidden

Antonio Diaz, tarlz author and maintainer.
Self-determination is a right, not a crime. Free Catalan political prisoners.
If you care about long-term archiving, please help me replace xz with lzip. See http://www.nongnu.org/lzip/lzip_benchmark.html#xz1
http://www.nongnu.org/lzip/manual/lzip_manual.html#Quality-assurance and
http://www.nongnu.org/lzip/xz_inadequate.html Thanks.

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