table of contents
|GEOM_UZIP(4)||Device Drivers Manual||GEOM_UZIP(4)|
geom_uzip — GEOM
based compressed disk images and partitions
To compile this driver into the kernel, place the following line in your kernel configuration file:
Alternatively, to load the driver as a module at boot time, place the following line in loader.conf(5):
geom_uzip framework provides support
for compressed read-only disk images. This allows significant storage
savings at the expense of a some CPU time on each read. Data written in the
GEOM label area allows
geom_uzip to detect
compressed images which have been created with mkuzip(8)
and presented to the kernel as a logical disk device via
geom_uzip creates a unique
md#.uzip device for each image.
geom_uzip is not limited to supporting
only md(4) images. The image can also reside on a block
device. (For example, a disk, USB flash drive, DVD-ROM, etc.) The
appropriate device node will appear with the .uzip
# gpart show da0 => 0 7833600 da0 BSD (3.7G) 0 2097152 1 freebsd-ufs (1.0G) 2097152 5736448 - free - (2.7G) # gpart add -t freebsd-ufs -s 1G da0 da0b added # dd if=/tmp/20160217_dcomp_zcomp.uzip bs=256k of=/dev/da0b 3190+1 records in 3190+1 records out 836331008 bytes transferred in 111.021489 secs (7533055 bytes/sec) # fsck -t ffs /dev/da0b.uzip ** /dev/da0b.uzip (NO WRITE) ** Last Mounted on /mnt ** Phase 1 - Check Blocks and Sizes ** Phase 2 - Check Pathnames ** Phase 3 - Check Connectivity ** Phase 4 - Check Reference Counts ** Phase 5 - Check Cyl groups 97455 files, 604242 used, 184741 free (2349 frags, 22799 blocks, 0.3% fragmentation) # mount -o ro /dev/da0b.uzip /mnt # df /dev/da0b.uzip Filesystem 1K-blocks Used Avail Capacity Mounted on /dev/da0b.uzip 3155932 2416968 738964 77% /mnt
geom_uzip device is subsequently used
by FreeBSD kernel to access the uncompressed data.
geom_uzip driver does not allow write operations
to the underlying disk image. To check which “providers” match
# geom uzip list Geom name: md1.uzip Providers: 1. Name: md1.uzip Mediasize: 22003712 (21M) Sectorsize: 512 Consumers: 1. Name: md1 Mediasize: 9563648 (9.1M) Sectorsize: 512 Geom name: da0b.uzip Providers: 1. Name: da0b.uzip Mediasize: 3355443200 (3.1G) Sectorsize: 512 Consumers: 1. Name: da0b Mediasize: 1073741824 (1.0G) Sectorsize: 512
geom_uzip allows mounting the root file
system from a compressed disk partition by setting the
vfs.root.mountfrom tunable. See
loader.conf(5) for details.
Several flags are provided for tracing
geom_uzip I/O operations and TOC parsing via the
- Log level. Zero disables logging. Higher values enable more verbose debug
geom_uzip. Supported levels are from 0 (no logging) to 4 (maximum amount of logging).
- Log operations involving compressed cluster number.
geom_uzip driver was written by
The block de-duplication code as well as some
geom_uzip driver optimizations have been contributed
by Maxim Sobolev
The LZMA decompression support and CLOOP 3.0 support have been added by
This manual page was written by Ceri Davies <ceri@FreeBSD.org>.
|February 26, 2019||Debian|