systemd-repart(8) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | SEE ALSO | COLOPHON

SYSTEMD-REPART(8)              systemd-repart              SYSTEMD-REPART(8)

NAME         top

       systemd-repart, systemd-repart.service - Automatically grow and add
       partitions

SYNOPSIS         top

       systemd-repart [OPTIONS...] [[BLOCKDEVICE]...]

       systemd-repart.service

DESCRIPTION         top

       systemd-repart grows and adds partitions to a partition table, based
       on the configuration files described in repart.d(5).

       If invoked with no arguments, it operates on the block device backing
       the root file system partition of the OS, thus growing and adding
       partitions of the booted OS image itself. When called in the initial
       RAM disk it operates on the block device backing /sysroot/ instead,
       i.e. on the block device the system will soon transition into. The
       systemd-repart.service service is generally run at boot in the
       initial RAM disk, in order to augment the partition table of the OS
       before its partitions are mounted.  systemd-repart (mostly) operates
       in a purely incremental mode: it only grows existing and adds new
       partitions; it does not shrink, delete or move existing partitions.
       The service is intended to be run on every boot, but when it detects
       that the partition table already matches the installed
       repart.d/*.conf configuration files, it executes no operation.

       systemd-repart is intended to be used when deploying OS images, to
       automatically adjust them to the system they are running on, during
       first boot. This way the deployed image can be minimal in size and
       may be augmented automatically at boot when needed, taking possession
       of disk space available but not yet used. Specifically the following
       use cases are among those covered:

       ·   The root partition may be grown to cover the whole available disk
           space

       ·   A /home/, swap or /srv/ partition can be added in

       ·   A second (or third, ...) root partition may be added in, to cover
           A/B style setups where a second version of the root file system
           is alternatingly used for implementing update schemes. The
           deployed image would carry only a single partition ("A") but on
           first boot a second partition ("B") for this purpose is
           automatically created.

       The algorithm executed by systemd-repart is roughly as follows:

        1. The repart.d/*.conf configuration files are loaded and parsed,
           and ordered by filename (without the directory suffix).

        2. The partition table already existing on the block device is
           loaded and parsed.

        3. The existing partitions in the partition table are matched up
           with the repart.d/*.conf files by GPT partition type UUID. The
           first existing partition of a specific type is assigned the first
           configuration file declaring the same type. The second existing
           partition of a specific type is then assigned the second
           configuration file declaring the same type, and so on. After this
           iterative assigning is complete any left-over existing partitions
           that have no matching configuration file are considered "foreign"
           and left as they are. And any configuration files for which no
           partition currently exists are understood as a request to create
           such a partition.

        4. Taking the size constraints and weights declared in the
           configuration files into account, all partitions that shall be
           created are now allocated to the disk, taking up all free space,
           always respecting the size and padding requests. Similar,
           existing partitions that are determined to grow are grown. New
           partitions are always appended to the end of the existing
           partition table, taking the first partition table slot whose
           index is greater than the indexes of all existing partitions.
           Partition table slots are never reordered and thus partition
           numbers are ensured to remain stable. Note that this allocation
           happens in RAM only, the partition table on disk is not updated
           yet.

        5. All existing partitions for which configuration files exist and
           which currently have no GPT partition label set will be assigned
           a label, either explicitly configured in the configuration or (if
           that's missing) derived automatically from the partition type.
           The same is done for all partitions that are newly created. These
           assignments are done in RAM only, too, the disk is not updated
           yet.

        6. Similarly, all existing partitions for which configuration files
           exist and which currently have an all-zero identifying UUID will
           be assigned a new UUID. This UUID is cryptographically hashed
           from a common seed value together with the partition type UUID
           (and a counter in case multiple partitions of the same type are
           defined), see below. The same is done for all partitions that are
           created anew. These assignments are done in RAM only, too, the
           disk is not updated yet.

        7. Similarly, if the disk's volume UUID is all zeroes it is also
           initialized, also cryptographically hashed from the same common
           seed value. Also, in RAM only, too.

        8. The disk space assigned to new partitions (i.e. what was
           previously considered free space but is no longer) is now erased.
           Specifically, all file system signatures are removed, and if the
           device supports it the BLKDISCARD I/O control command is issued
           to inform the hardware that the space is empty now. In addition
           any "padding" between partitions and at the end of the device is
           similarly erased.

        9. The new partition table is finally written to disk. The kernel is
           asked to reread the partition table.

       As exception to the normally strictly incremental operation, when
       called in a special "factory reset" mode systemd-repart may also be
       used to erase select existing partitions to reset an installation
       back to vendor defaults. This mode of operation is used when either
       the --factory-reset=yes switch is passed on the tool's command line,
       or the systemd.factory_reset=yes option specified on the kernel
       command line, or the FactoryReset EFI variable (vendor UUID
       8cf2644b-4b0b-428f-9387-6d876050dc67) is set to "yes". It alters the
       algorithm above slightly: between the 3rd and the 4th step above the
       any partition marked explicitly via the FactoryReset= boolean is
       deleted, and the algorithm restarted, thus immediately re-creating
       these partitions anew empty.

       Note that systemd-repart only changes partition tables, it does not
       create or resize any file systems within these partitions. A separate
       mechanism should be used for that, for example systemd-growfs(8) and
       systemd-makefs.

       The UUIDs identifying the new partitions created (or assigned to
       existing partitions that have no UUID yet), as well as the disk as a
       whole are hashed cryptographically from a common seed value. This
       seed value is usually the machine-id(5) of the system, so that the
       machine ID reproducibly determines the UUIDs assigned to all
       partitions. If the machine ID cannot be read (or the user passes
       --seed=random, see below) the seed is generated randomly instead, so
       that the partition UUIDs are also effectively random. The seed value
       may also be set explicitly, formatted as UUID via the --seed= option.
       By hashing these UUIDs from a common seed images prepared with this
       tool become reproducible and the result of the algorithm above
       deterministic.

       The positional argument should specify the block device to operate
       on. Instead of a block device node path a regular file may be
       specified too, in which case the command operates on it like it would
       if a loopback block device node was specified with the file attached.
       If --empty=create is specified the specified path is created as
       regular file, which is useful for generating disk images from
       scratch.

OPTIONS         top

       The following options are understood:

       --dry-run=
           Takes a boolean. If this switch is not specified --dry-run=yes is
           the implied default. Controls whether systemd-repart executes the
           requested re-partition operations or whether it should only show
           what it would do. Unless --dry-run=no is specified systemd-repart
           will not actually touch the device's partition table.

       --empty=
           Takes one of "refuse", "allow", "require", "force" or "create".
           Controls how to operate on block devices that are entirely empty,
           i.e. carry no partition table/disk label yet. If this switch is
           not specified the implied default is "refuse".

           If "refuse" systemd-repart requires that the block device it
           shall operate on already carries a partition table and refuses
           operation if none is found. If "allow" the command will extend an
           existing partition table or create a new one if none exists. If
           "require" the command will create a new partition table if none
           exists so far, and refuse operation if one already exists. If
           "force" it will create a fresh partition table unconditionally,
           erasing the disk fully in effect. If "force" no existing
           partitions will be taken into account or survive the operation.
           Hence: use with care, this is a great way to lose all your data.
           If "create" a new loopback file is create under the path passed
           via the device node parameter, of the size indicated with
           --size=, see below.

       --discard=
           Takes a boolean. If this switch is not specified --discard=yes is
           the implied default. Controls whether to issue the BLKDISCARD I/O
           control command on the space taken up by any added partitions or
           on the space in between them. Usually, it's a good idea to issue
           this request since it tells the underlying hardware that the
           covered blocks shall be considered empty, improving performance.
           If operating on a regular file instead of a block device node, a
           sparse file is generated.

       --size=
           Takes a size in bytes, using the usual K, M, G, T suffixes. If
           used the specified device node path must refer to a regular file,
           which is then grown to the specified size if smaller, before any
           change is made to the partition table. This is not supported if
           the specified node is a block device. This switch has no effect
           if the file is already as large as the specified size or larger.
           The specified size is implicitly rounded up to multiples of 4096.
           When used with --empty=create this specifies the initial size of
           the loopback file to create.

       --factory-reset=
           Takes boolean. If this switch is not specified --factory=reset=no
           is the implied default. Controls whether to operate in "factory
           reset" mode, see above. If set to true this will remove all
           existing partitions marked with FactoryReset= set to yes early
           while executing the re-partitioning algorithm. Use with care,
           this is a great way to lose all your data. Note that partition
           files need to explicitly turn FactoryReset= on, as the option
           defaults to off. If no partitions are marked for factory reset
           this switch has no effect. Note that there are two other methods
           to request factory reset operation: via the kernel command line
           and via an EFI variable, see above.

       --can-factory-reset
           If this switch is specified the disk is not re-partitioned.
           Instead it is determined if any existing partitions are marked
           with FactoryReset=. If there are the tool will exit with exit
           status zero, otherwise non-zero. This switch may be used to
           quickly determine whether the running system supports a factory
           reset mechanism built on systemd-repart.

       --root=
           Takes a path to a directory to use as root file system when
           searching for repart.d/*.conf files and for the machine ID file
           to use as seed. By default when invoked on the regular system
           this defaults to the host's root file system /. If invoked from
           the initial RAM disk this defaults to /sysroot/, so that the tool
           operates on the configuration and machine ID stored in the root
           file system later transitioned into itself.

       --seed=
           Takes a UUID as argument or the special value random. If a UUID
           is specified the UUIDs to assign to partitions and the partition
           table itself are derived via cryptographic hashing from it. If
           not specified it is attempted to read the machine ID from the
           host (or more precisely, the root directory configured via
           --root=) and use it as seed instead, falling back to a randomized
           seed otherwise. Use --seed=random to force a randomized seed.
           Explicitly specifying the seed may be used to generated strictly
           reproducible partition tables.

       --pretty=
           Takes a boolean argument. If this switch is not specified, it
           defaults to on when called from an interactive terminal and off
           otherwise. Controls whether to show a user friendly table and
           graphic illustrating the changes applied.

       --definitions=
           Takes a file system path. If specified the *.conf are directly
           read from the specified directory instead of searching in
           /usr/lib/repart.d/*.conf, /etc/repart.d/*.conf,
           /run/repart.d/*.conf.

       -h, --help
           Print a short help text and exit.

       --version
           Print a short version string and exit.

SEE ALSO         top

       systemd(1), repart.d(5), machine-id(5)

COLOPHON         top

       This page is part of the systemd (systemd system and service manager)
       project.  Information about the project can be found at 
       ⟨http://www.freedesktop.org/wiki/Software/systemd⟩.  If you have a bug
       report for this manual page, see
       ⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.  This
       page was obtained from the project's upstream Git repository
       ⟨https://github.com/systemd/systemd.git⟩ on 2020-06-09.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-06-09.)  If you discover any rendering problems in
       this HTML version of the page, or you believe there is a better or
       more up-to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not part
       of the original manual page), send a mail to man-pages@man7.org

systemd 245                                                SYSTEMD-REPART(8)

Pages that refer to this page: repart.d(5)30-systemd-environment-d-generator(7)systemd.directives(7)systemd.index(7)systemd-growfs(8)systemd-growfs.service(8)systemd-growfs@.service(8)systemd-makefs(8)systemd-makefs.service(8)systemd-makefs@.service(8)systemd-mkswap.service(8)systemd-mkswap@.service(8)