Ubuntu Manpage: nbdkit-partitioning-plugin - create virtual disk from partitions

Provided by: nbdkit_1.24.1-2ubuntu4_amd64

NAME

       nbdkit-partitioning-plugin - create virtual disk from partitions

SYNOPSIS

        nbdkit partitioning [file=]part1 [[file=]part2 [file=]part3 ...]
                            [partition-type=mbr|gpt]

DESCRIPTION

"nbdkit-partitioning-plugin" is a plugin for nbdkit(1) which creates a partitioned virtual drive from a
list of one or more files each containing single partitions. The plugin concatenates the files together
and generates a virtual partition table so that NBD clients see a single partitioned disk.

If you just want to concatenate files together (without adding a partition table) use
nbdkit-split-plugin(1). If you want to select a single partition from an existing disk, use
nbdkit-partition-filter(1). If you want to create a complete disk with a filesystem, look at
nbdkit-floppy-plugin(1), nbdkit-iso-plugin(1) or nbdkit-linuxdisk-plugin(1).

The plugin supports read/write access. To limit clients to read-only access use the -r flag.

Partition table type
Using the "partition-type" parameter you can choose either an MBR or a GPT partition table. If this
parameter is not present then:

number of files > 4
⇒ GPT

else, total file size is larger than supported by MBR (approx. 2 TB)
⇒ GPT

otherwise
⇒ MBR (for maximum compatibility with clients)

Type of each partition
The type of each partition is controlled by a partition type byte (for MBR) or a partition type GUID (for
GPT). This can be set using the "mbr-id" or "type-guid" parameters respectively and affects the type of
all following files.

Padding and alignment
Partition sizes are automatically rounded up to a multiple of the 512 byte sector size.

Padding may be added between partitions to provide the best alignment. This is controlled by the
"alignment" parameter, which affects the alignment of all following files.

Writing to the virtual disk
NBD clients may read and write freely to partitions. Writes are propagated through to the underlying
files.

NBD clients may read from the virtual partition table, and padding areas of the virtual disk. When
reading from padding areas, clients will see zeroes.

NBD clients will get an I/O error if they try to change the virtual partition table or padding areas.

EXAMPLES

       From  a  bare  filesystem  stored in a file, create a virtual disk with a single partition containing the
       filesystem:

        nbdkit partitioning ext4fs.img

       Create a virtual disk containing boot, swap and root partitions:

        nbdkit partitioning \
                   boot.img \
                   mbr-id=0x82 swap.img mbr-id=default \
                   root.img

       This will not be bootable since the virtual partition table does  not  contain  a  boot  sector  or  boot
       loader.

       Notice  that  the swap partition is bracketed by "mbr-id=0x82" to set the MBR partition type byte to 0x82
       (Linux swap) for the swap partition, followed by "mbr-id=default" to set the MBR partition type byte back
       to the default (0x83, Linux filesystem) for the remaining partition.

       If file.raw has a size which is a multiple of 512 bytes then this is a  no-op  because  the  partitioning
       plugin adds a partition table which is then removed by nbdkit-partition-filter(1):

        nbdkit --filter=partition partitioning file.raw partition=1

PARAMETERS

[file=]FILENAME
One or more files containing partition data.

This parameter is required.

"file=" is a magic config key and may be omitted in most cases. See "Magic parameters" in nbdkit(1).

partition-type=mbr
Add an MBR (DOS-style) partition table. The MBR format is maximally compatible with all clients.

If there are > 4 partitions then the first three files are mapped to primary partitions, an extended
partition (https://en.wikipedia.org/wiki/Extended_boot_record) is created as partition 4, and the
files starting from the 4th will appear as partition 5 and upwards.

partition-type=gpt
Add a GPT partition table. Note that as well as the virtual primary partition table added at the
beginning of the disk, a virtual secondary partition table is added at the end, as required by GPT.
Also this adds a "protective MBR" as defined by the UEFI spec so that old clients which don't
understand GPT will ignore the partitions.

alignment=N
Set the alignment of all following files to "N" bytes. The default alignment is 1M (2048 sectors).

mbr-id=0xN
Set the MBR type byte of all following files to "0xN". Type bytes are normally specified in
hexadecimal, and you must use the "0x" prefix to indicate this.

mbr-id=default
Set the MBR type byte back to the default, 0x83 which indicates a Linux filesystem.

type-guid=GUID
Set the GPT partition type GUID of all following files to "GUID".

type-guid=default
Set the GPT partition type GUID back to the default, "0FC63DAF-8483-4772-8E79-3D69D8477DE4" which
indicates a Linux filesystem.

LIMITS

       Although this plugin can create GPT partition tables containing more than 128 GPT  partitions  (in  fact,
       unlimited numbers of partitions), some clients will not be able to handle this.

       Zero length partitions are not allowed and will cause nbdkit to exit with an error when it starts up.

       The sector size is fixed at 512 bytes.

FILES

       $plugindir/nbdkit-partitioning-plugin.so
           The plugin.

           Use "nbdkit --dump-config" to find the location of $plugindir.

VERSION

       "nbdkit-partitioning-plugin" first appeared in nbdkit 1.8.

AUTHORS

       Richard W.M. Jones

COPYRIGHT

       Copyright (C) 2018 Red Hat Inc.

LICENSE

       Redistribution and use in source and binary forms, with or without modification, are  permitted  provided
       that the following conditions are met:

       •   Redistributions  of  source  code must retain the above copyright notice, this list of conditions and
           the following disclaimer.

       •   Redistributions in binary form must reproduce the above copyright notice, this list of conditions and
           the following disclaimer in the documentation and/or other materials provided with the distribution.

       •   Neither the name of Red Hat nor the names of its contributors may  be  used  to  endorse  or  promote
           products derived from this software without specific prior written permission.

       THIS  SOFTWARE  IS  PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
       INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND  FITNESS  FOR  A  PARTICULAR
       PURPOSE  ARE  DISCLAIMED.  IN  NO EVENT SHALL RED HAT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
       INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,  PROCUREMENT  OF
       SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
       ON  ANY  THEORY  OF  LIABILITY,  WHETHER  IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
       OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
       DAMAGE.

nbdkit-1.24.1                                      2021-01-20                      nbdkit-partitioning-plugin(1)