nbdkit-partitioning-plugin(1) NBDKIT nbdkit-partitioning-plugin(1) 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 par- titioned virtual drive from a list of one or more files each containing single partitions. The plugin concatenates the files together and gener- ates 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 parti- tion 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 ac- cess 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 a GPT else, total file size is larger than supported by MBR (approx. 2 TB) a GPT otherwise a 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 align- ment 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 ze- roes. NBD clients will get an I/O error if they try to change the virtual parti- tion table or padding areas. EXAMPLES From a bare filesystem stored in a file, create a virtual disk with a sin- gle 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 con- tain 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=" prefix 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 par- tition 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 filesys- tem. 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. SEE ALSO nbdkit(1), nbdkit-file-plugin(1), nbdkit-floppy-plugin(1), nbdkit-iso-plu- gin(1), nbdkit-linuxdisk-plugin(1), nbdkit-partition-filter(1), nbd- kit-split-plugin(1), nbdkit-plugin(3). AUTHORS Richard W.M. Jones COPYRIGHT Copyright Red Hat LICENSE Redistribution and use in source and binary forms, with or without modifi- cation, 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 no- tice, this list of conditions and the following disclaimer in the docu- mentation 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 EX- PRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DIS- CLAIMED. IN NO EVENT SHALL RED HAT OR CONTRIBUTORS BE LIABLE FOR ANY DI- RECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SER- VICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABIL- ITY, 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 DAM- AGE. nbdkit-1.46.2 2026-08-30 nbdkit-partitioning-plugin(1)
NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | PARAMETERS | LIMITS | FILES | VERSION | SEE ALSO | AUTHORS | COPYRIGHT | LICENSE
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