GEOM_UNCOMPRESS(4) BSD 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>.
BSD
January 9, 2014 BSD