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).

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

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=0x83 \
            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=0x83" to set the MBR partition type byte back to 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=" may be omitted. To ensure that the filename does not end up being parsed accidentally as "key=value", prefix relative paths with "./" (absolute paths do not need modification).

partition-type=mbr

Add an MBR (DOS-style) partition table. The MBR format is maximally compatible with all clients, but only supports up to 4 partitions.

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. The default is 0x83 which indicates a Linux filesystem.

type-guid=GUID

Set the GPT partition type GUID of all following files to "GUID". The default is "0FC63DAF-8483-4772-8E79-3D69D8477DE4" which indicates a Linux filesystem.

LIMITS¶

This plugin only supports primary MBR partitions, hence the limit of 4 partitions with MBR. This might be increased in future if we implement support for logical/extended MBR partitions.

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.

The sector size is fixed at 512 bytes.

SEE ALSO¶

nbdkit(1), nbdkit-file-plugin(1), nbdkit-partition-filter(1), nbdkit-split-plugin(1), nbdkit-plugin(3).

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.

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