Copyright (c) 2006 Ceri Davies All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other ...
NAMEgeom_uzip - GEOM based compressed disk images and partitions
SYNOPSISTo 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.conf5:
DESCRIPTIONThe 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 to detect compressed images which have been created with mkuzip(8) and presented to the kernel as a logical disk device via md(4). creates a unique md#.uzip device for each image.
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 suffix.
# 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
The device is subsequently used by Fx kernel to access the uncompressed data. The driver does not allow write operations to the underlying disk image. To check which ``providers'' match a given device:
# 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
allows mounting the root file system from a compressed disk partition by setting the vfs.root.mountfrom tunable. See loader.conf5 for details.
DIAGNOSTICSSeveral flags are provided for tracing I/O operations and TOC parsing via the following sysctls.
- Log level. Zero disables logging. Higher values enable more verbose debug logging for . Supported levels are from 0 (no logging) to 4 (maximum amount of logging).
- Log operations involving compressed cluster number.
SEE ALSOGEOM(4), md(4), geom(8), mkuzip(8)
AUTHORSAn -nosplit The driver was written by An Max Khon Aq Mt fjoe@FreeBSD.org . The block de-duplication code as well as some driver optimizations have been contributed by An Maxim Sobolev Aq Mt sobomax@FreeBSD.org . The LZMA decompression support and CLOOP 3.0 support have been added by An Aleksandr Rybalko Aq Mt ray@FreeBSD.org .
This manual page was written by An Ceri Davies Aq Mt ceri@FreeBSD.org .