systemd-repart, systemd-repart.service - Automatically grow and add partitions
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
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
•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
The algorithm executed by systemd-repart is roughly as
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
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
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:
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.
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
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.
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.
Takes a size in bytes, using the usual K, M, G, T
suffixes, or the special value "auto". 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. If
specified as "auto" the minimal size for the disk image is
automatically determined (i.e. the minimal sizes of all partitions are summed
up, taking space for additional metadata into account). This switch 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
this specifies the initial size of the loopback file to
The --size=auto option takes the sizes of pre-existing
partitions into account. However, it does not accommodate for partition
tables that are not tightly packed: the configured partitions might still
not fit into the backing device if empty space exists between pre-existing
partitions (or before the first partition) that cannot be fully filled by
partitions to grow or create.
Also note that the automatic size determination does not take
files or directories specified with CopyFiles= into account:
operation might fail if the specified files or directories require more disk
space then the configured per-partition minimal size limit.
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.
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
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.
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.
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.
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.
Takes a file system path. Configures the encryption key
to use when setting up LUKS2 volumes configured with the
Encrypt=key-file setting in partition files. Should refer to a regular
file containing the key, or an AF_UNIX stream socket in the file
system. In the latter case a connection is made to it and the key read from
it. If this switch is not specified the empty key (i.e. zero length key) is
used. This behaviour is useful for setting up encrypted partitions during
early first boot that receive their user-supplied password only in a later
Configures the TPM2 device and list of PCRs to use for
LUKS2 volumes configured with the Encrypt=tpm2
option. These options
take the same parameters as the identically named options to
and have the same effect on partitions where
TPM2 enrollment is requested.
Print a short help text and exit.
Print a short version string and exit.
Do not pipe output into a pager.
Do not print the legend, i.e. column headers and the
footer with hints.
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, the default).
On success, 0 is returned, a non-zero failure code otherwise.