[Lzip-bug] Tarlz 0.19 released

[Antonio Diaz Diaz]

I am pleased to announce the release of tarlz 0.19.

Tarlz is a massively parallel (multi-threaded) combined implementation of 
the tar archiver and the lzip compressor. Tarlz uses the compression library 
lzlib.

Tarlz creates tar archives using a simplified and safer variant of the POSIX 
pax format compressed in lzip format, keeping the alignment between tar 
members and lzip members. 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.

Keeping the alignment between tar members and lzip members has two 
advantages. It adds an indexed lzip layer on top of the tar archive, making 
it possible to decode the archive safely in parallel. It also minimizes the 
amount of data lost in case of corruption. Compressing a tar archive with 
plzip may even double the amount of files lost for each lzip member damaged 
because it does not keep the members aligned.

Tarlz can create tar archives with five levels of compression granularity: 
per file (--no-solid), per block (--bsolid, default), per directory 
(--dsolid), appendable solid (--asolid), and solid (--solid). It can also 
create uncompressed tar archives.

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), and unwanted members can be deleted from the archive.
      Just like 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
http://download.savannah.gnu.org/releases/lzip/tarlz/

The sha256sum is:
3639eb55f97be324efe90dcdbcc77a4851770363722425d5fd3b8e934aa1aa27 
tarlz-0.19.tar.lz


Changes in version 0.19:

  * A missing '#include <sys/types.h>', which made compilation fail on some 
systems, has been added.

  * At verbosity level 1 or higher tarlz now prints a diagnostic for each 
unknown extended header keyword found in an archive, once per keyword.


Please send bug reports and suggestions to lzip-bug@nongnu.org


Regards,
Antonio Diaz, tarlz author and maintainer.
Self-determination is a human right. Free Catalan political prisoners.
--
If you care about data safety and long-term archiving, please consider using 
lzip. See http://www.nongnu.org/lzip/lzip_benchmark.html
http://www.nongnu.org/lzip/manual/lzip_manual.html#Quality-assurance and
http://www.nongnu.org/lzip/safety_of_the_lzip_format.html Thanks.