NAME

       borg-compression - Details regarding compression

DESCRIPTION

       It  is  no problem to mix different compression methods in one repo, deduplication is done
       on the source data chunks (not on the compressed or encrypted data).

       If some specific chunk was once compressed and stored  into  the  repo,  creating  another
       backup  that  also  uses  this  chunk  will  not  change  the stored chunk.  So if you use
       different compression specs for the backups, whichever stores a chunk first determines its
       compression. See also borg recreate.

       Compression  is  lz4  by default. If you want something else, you have to specify what you
       want.

       Valid compression specifiers are:

       none   Do not compress.

       lz4    Use lz4 compression. Very high speed, very low compression. (default)

       zstd[,L]
              Use zstd ("zstandard") compression, a modern wide-range algorithm.  If you  do  not
              explicitely  give the compression level L (ranging from 1 to 22), it will use level
              3.  Archives compressed with zstd are not compatible with borg < 1.1.4.

       zlib[,L]
              Use zlib ("gz") compression. Medium speed,  medium  compression.   If  you  do  not
              explicitely  give  the compression level L (ranging from 0 to 9), it will use level
              6.  Giving level 0 (means "no compression", but still has zlib  protocol  overhead)
              is usually pointless, you better use "none" compression.

       lzma[,L]
              Use  lzma  ("xz")  compression.  Low  speed,  high  compression.   If  you  do  not
              explicitely give the compression level L (ranging from 0 to 9), it will  use  level
              6.   Giving  levels  above 6 is pointless and counterproductive because it does not
              compress better due to the buffer size used by borg - but it  wastes  lots  of  CPU
              cycles and RAM.

       auto,C[,L]
              Use  a  built-in  heuristic  to  decide  per chunk whether to compress or not.  The
              heuristic tries with lz4 whether the  data  is  compressible.   For  incompressible
              data,  it  will  not use compression (uses "none").  For compressible data, it uses
              the given C[,L] compression - with C[,L] being any valid compression specifier.

       Examples:

          borg create --compression lz4 REPO::ARCHIVE data
          borg create --compression zstd REPO::ARCHIVE data
          borg create --compression zstd,10 REPO::ARCHIVE data
          borg create --compression zlib REPO::ARCHIVE data
          borg create --compression zlib,1 REPO::ARCHIVE data
          borg create --compression auto,lzma,6 REPO::ARCHIVE data
          borg create --compression auto,lzma ...

AUTHOR

       The Borg Collective

                                            2020-12-24                        BORG-COMPRESSION(1)