nbdkit-linuxdisk-plugin(1)

1nbdkit-linuxdisk-plugin(1)          NBDKIT          nbdkit-linuxdisk-plugin(1)
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NAME

6       nbdkit-linuxdisk-plugin - create virtual Linux disk from directory
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SYNOPSIS

9        nbdkit linuxdisk [dir=]DIRECTORY
10                         [label=LABEL] [type=ext2|ext3|ext4]
11                         [size=[+]SIZE]
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DESCRIPTION

14       "nbdkit-linuxdisk-plugin" is a plugin for nbdkit(1) which creates an
15       ext2-, ext3- or ext4-formatted disk image from a directory on the fly.
16       The files in the specified directory (and subdirectories) appear in the
17       virtual disk, which is served read-only over the NBD protocol.
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19       The virtual disk is partitioned with a single GPT partition containing
20       the filesystem.
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22       The virtual disk can be used as a Linux root (or other) filesystem.
23       Most features of Linux filesystems are supported, such as hard links,
24       symbolic links, block special devices etc.
25
26       To create a FAT-formatted virtual floppy disk, see
27       nbdkit-floppy-plugin(1).  To create a CD/ISO, see nbdkit-iso-plugin(1).
28       To create an empty filesystem for each client that connects (like a
29       "remote tmpfs") use nbdkit-tmpdisk-plugin(1).
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EXAMPLES

32       nbdkit linuxdisk /path/to/directory label=ROOTFS
33           Create a virtual disk, giving it a filesystem label.  Note that
34           clients will not be able to modify the filesystem, so it is safe to
35           share it with multiple clients.
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37       nbdkit --filter=cow linuxdisk /path/to/directory
38           Add a writable overlay (see nbdkit-cow-filter(1), allowing the disk
39           to be written by the client.  Multiple clients must not be allowed
40           to connect at the same time (even if they all mount it read-only)
41           as this will cause disk corruption.
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43       nbdkit --filter=cow linuxdisk /path/to/directory size=+1G
44           The same but specifying that at least 1G of free space should be
45           available in the filesystem (not including the space taken by the
46           initial filesystem).
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48       nbdkit --filter=partition linuxdisk /path/to/directory partition=1
49           Instead of serving a partitioned disk image, serve just the "naked"
50           filesystem (ie. the first partition, see
51           nbdkit-partition-filter(1)).
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53       nbdkit -U - linuxdisk /path/to/directory --run 'nbdcopy "$uri"
54       ext2fs.img'
55           This serves nothing.  Instead it turns a directory into a disk
56           image, writing it to ext2fs.img (see nbdkit-captive(1)).  The
57           resulting image is a partitioned disk.
58
59       Create a minimal virtual appliance
60           This creates and boots a minimal busybox(1)-based virtual
61           appliance.  This assumes that your kernel (/boot/vmlinuz) contains
62           the ext2 or ext4 driver compiled in, but most Linux distro kernels
63           have that.
64
65            mkdir -p root/{bin,dev,proc,sbin,sys,usr/bin,usr/sbin}
66            sudo mknod root/dev/console c 5 1
67            cp /sbin/busybox root/sbin/
68            ln root/sbin/busybox root/sbin/init
69            ln root/sbin/busybox root/bin/ls
70            ln root/sbin/busybox root/bin/sh
71            nbdkit -U - linuxdisk root --run '
72              qemu-kvm -display none -kernel /boot/vmlinuz -drive file=nbd:unix:$unixsocket,snapshot=on -append "console=ttyS0 root=/dev/sda1 rw" -serial stdio
73            '
74
75           You can drop any extra files you need into the root/ directory and
76           they will be copied into the appliance before boot.  After booting
77           type these commands to complete the environmental setup:
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79            /sbin/busybox --install
80            mount -t proc proc /proc
81            mount -t sysfs sys /sys
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PARAMETERS

84       [dir=]DIRECTORY
85           Specify the directory containing files and subdirectories which
86           will be added to the virtual disk.  Files inside this directory
87           will appear in the root directory of the virtual disk.
88
89           This parameter is required.
90
91           "dir=" is a magic config key and may be omitted in most cases.  See
92           "Magic parameters" in nbdkit(1).
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94       label=LABEL
95           The optional label for the filesystem.
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97       size=SIZE
98       size=+SIZE
99           The total (virtual) size of the filesystem.
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101           If the "size" parameter is omitted the plugin will try to size the
102           filesystem with just enough space to contain the files and
103           directories that are initially loaded, and there will not be much
104           extra space.
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106           Using "size=SIZE" specifies the required virtual size of the whole
107           filesystem (including initial files and extra space).  If this is
108           set too small for the initial filesystem then the plugin will fail
109           to start.
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111           Using "size=+SIZE" specifies the minimum free space required after
112           the initial filesystem has been loaded.  (The actual free space
113           might be slightly larger).
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115       type=ext2
116       type=ext3
117       type=ext4
118           Select the filesystem type.  The default is "ext2".
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NOTES

121   Users and groups
122       The original file UIDs and GIDs are recreated as far as possible.  Note
123       that UIDs/GIDs will likely map to different users and groups when read
124       by a virtual machine or other NBD client machine.
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ENVIRONMENT VARIABLES

127       "TMPDIR"
128           The filesystem image is stored in a temporary file located in
129           /var/tmp by default.  You can override this location by setting the
130           "TMPDIR" environment variable before starting nbdkit.
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FILES

133       $plugindir/nbdkit-linuxdisk-plugin.so
134           The plugin.
135
136           Use "nbdkit --dump-config" to find the location of $plugindir.
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VERSION

139       "nbdkit-linuxdisk-plugin" first appeared in nbdkit 1.12.
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AUTHORS

148       Richard W.M. Jones
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COPYRIGHT

151       Copyright (C) 2019 Red Hat Inc.
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LICENSE

154       Redistribution and use in source and binary forms, with or without
155       modification, are permitted provided that the following conditions are
156       met:
157
158       •   Redistributions of source code must retain the above copyright
159           notice, this list of conditions and the following disclaimer.
160
161       •   Redistributions in binary form must reproduce the above copyright
162           notice, this list of conditions and the following disclaimer in the
163           documentation and/or other materials provided with the
164           distribution.
165
166       •   Neither the name of Red Hat nor the names of its contributors may
167           be used to endorse or promote products derived from this software
168           without specific prior written permission.
169
170       THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND ANY
171       EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
172       IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
173       PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR CONTRIBUTORS BE
174       LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
175       CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
176       SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
177       BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
178       WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
179       OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
180       ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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184nbdkit-1.25.8                     2021-05-25        nbdkit-linuxdisk-plugin(1)