xref: /freebsd/share/man/man4/geom_uzip.4 (revision f0a75d274af375d15b97b830966b99a02b7db911)
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26.\" $FreeBSD$
27.\"
28.Dd October 9, 2006
29.Os
30.Dt GEOM_UZIP 4
31.Sh NAME
32.Nm geom_uzip
33.Nd "GEOM based compressed disk images"
34.Sh SYNOPSIS
35To compile this driver into the kernel,
36place the following line in your
37kernel configuration file:
38.Bd -ragged -offset indent
39.Cd "options GEOM_UZIP"
40.Ed
41.Pp
42Alternatively, to load the driver as a
43module at boot time, place the following line in
44.Xr loader.conf 5 :
45.Bd -literal -offset indent
46geom_uzip_load="YES"
47.Ed
48.Sh DESCRIPTION
49The
50.Nm
51framework provides support for compressed read only
52disk images.
53This allows significant storage savings at the expense of
54a little CPU time on each read.
55Data written in the GEOM label area allows
56.Nm
57to detect compressed images which have been created with
58.Xr mkuzip 8
59and presented to the kernel as a logical disk device via
60.Xr md 4 .
61.Nm
62creates a unique
63.Pa md#.uzip
64device for each image.
65.Pp
66The
67.Nm
68device is subsequently used by the
69.Fx
70kernel to access the disk images.
71The
72.Nm
73driver does not allow write operations to the underlying disk image.
74To check which
75.Xr md 4
76devices match a given
77.Nm
78device:
79.Bd -literal -offset indent
80# geom uzip list
81Geom name: md1.uzip
82Providers:
831. Name: md1.uzip
84   Mediasize: 22003712 (21M)
85   Sectorsize: 512
86   Mode: r1w0e1
87Consumers:
881. Name: md1
89   Mediasize: 9563648 (9.1M)
90   Sectorsize: 512
91   Mode: r1w0e1
92.Ed
93.Pp
94.Sh SEE ALSO
95.Xr GEOM 4 ,
96.Xr md 4 ,
97.Xr geom 8 ,
98.Xr mkuzip 8
99.Sh AUTHORS
100.An -nosplit
101The
102.Nm
103driver was written by
104.An "Max Khon" Aq fjoe@FreeBSD.org .
105This manual page was written by
106.An "Ceri Davies" Aq ceri@FreeBSD.org .
107