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GEOM_UNCOMPRESS(4)     FreeBSD Kernel Interfaces Manual     GEOM_UNCOMPRESS(4)

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>.

FreeBSD 11.0-PRERELEASE         January 9, 2014        FreeBSD 11.0-PRERELEASE

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | AUTHORS

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