NAME

       geom_uncompress — GEOM based compressed disk images

SYNOPSIS

       To compile this driver into the kernel, place the following line in your kernel configuration file:

             options GEOM_UNCOMPRESS

       Alternatively, to load the driver as a module at boot time, place the following line in loader.conf(5):

             geom_uncompress_load="YES"

DESCRIPTION

       The  geom_uncompress  framework  provides  support  for  compressed  read  only disk images.  This allows
       significant storage savings at the expense of a little CPU time on each read.  Data written in  the  GEOM
       label  area allows geom_uncompress to detect compressed images which have been created with mkulzma(8) or
       mkuzip(8) and presented to the kernel as a logical disk device  via  md(4).   geom_uncompress  creates  a
       unique md#.uncompress device for each image.

       The  geom_uncompress  device  is  subsequently used by the FreeBSD kernel to access the disk images.  The
       geom_uncompress driver does not allow write operations to the underlying  disk  image.   To  check  which
       md(4) devices match a given geom_uncompress device:

             # geom uncompress list
             Geom name: md0.uncompress
             Providers:
             1. Name: md0.uncompress
                Mediasize: 52428800 (50M)
                Sectorsize: 512
                Mode: r1w0e0
             Consumers:
             1. Name: md0
                Mediasize: 20864000 (20M)
                Sectorsize: 512
                Mode: r1w0e0

SEE ALSO

       GEOM(4), md(4), geom(8), mkulzma(8), mkuzip(8)

AUTHORS

       The  geom_uncompress  driver  was  written  by  Maxim Sobolev <sobomax@FreeBSD.org> and Aleksandr Rybalko
       <ray@FreeBSD.org>.  This manual page was written by Luiz Otavio O Souza <loos@FreeBSD.org>.

Debian                                           January 9, 2014                              GEOM_UNCOMPRESS(4)