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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | SEE ALSO | COLOPHON |
SYSTEMD-REPART(8) systemd-repart SYSTEMD-REPART(8)
systemd-repart, systemd-repart.service - Automatically grow and add
partitions
systemd-repart [OPTIONS...] [[BLOCKDEVICE]...]
systemd-repart.service
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.
· A second (or third, ...) root partition may be added, 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 prefix).
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 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 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.
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.
--json=MODE
Shows output formatted as JSON. Expects one of "short" (for the
shortest possible output without any redundant whitespace or line
breaks), "pretty" (for a pretty version of the same, with
indentation and line breaks) or "off" (to turn off json output).
--definitions=
Takes a file system path. If specified the *.conf files are 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.
systemd(1), repart.d(5), machine-id(5)
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 2020-08-13. (At that
time, the date of the most recent commit that was found in the repos‐
itory was 2020-08-11.) 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 246 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)