2 <!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
4 <refentry id=
"repart.d" conditional='ENABLE_REPART'
>
7 <title>repart.d
</title>
8 <productname>systemd
</productname>
12 <refentrytitle>repart.d
</refentrytitle>
13 <manvolnum>5</manvolnum>
17 <refname>repart.d
</refname>
18 <refpurpose>Partition Definition Files for Automatic Boot-Time Repartitioning
</refpurpose>
22 <para><literallayout><filename>/etc/repart.d/*.conf
</filename>
23 <filename>/run/repart.d/*.conf
</filename>
24 <filename>/usr/lib/repart.d/*.conf
</filename>
25 </literallayout></para>
29 <title>Description
</title>
31 <para><filename>repart.d/*.conf
</filename> files describe basic properties of partitions of block
32 devices of the local system. They may be used to declare types, names and sizes of partitions that shall
34 <citerefentry><refentrytitle>systemd-repart
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
35 service reads these files and attempts to add new partitions currently missing and enlarge existing
36 partitions according to these definitions. Operation is generally incremental, i.e. when applied, what
37 exists already is left intact, and partitions are never shrunk, moved or deleted.
</para>
39 <para>These definition files are useful for implementing operating system images that are prepared and
40 delivered with minimally sized images (for example lacking any state or swap partitions), and which on
41 first boot automatically take possession of any remaining disk space following a few basic rules.
</para>
43 <para>Currently, support for partition definition files is only implemented for GPT partitition
46 <para>Partition files are generally matched against any partitions already existing on disk in a simple
47 algorithm: the partition files are sorted by their filename (ignoring the directory prefix), and then
48 compared in order against existing partitions matching the same partition type UUID. Specifically, the
49 first existing partition with a specific partition type UUID is assigned the first definition file with
50 the same partition type UUID, and the second existing partition with a specific type UUID the second
51 partition file with the same type UUID, and so on. Any left-over partition files that have no matching
52 existing partition are assumed to define new partition that shall be created. Such partitions are
53 appended to the end of the partition table, in the order defined by their names utilizing the first
54 partition slot greater than the highest slot number currently in use. Any existing partitions that have
55 no matching partition file are left as they are.
</para>
57 <para>Note that these partition definition files do not describe the contents of the partitions, such as
58 the file system used. Separate mechanisms, such as
59 <citerefentry><refentrytitle>systemd-growfs
</refentrytitle><manvolnum>8</manvolnum></citerefentry> and
60 <command>systemd-makefs
</command> maybe be used to initialize or grow the file systems inside of these
65 <title>[Partition] Section Options
</title>
69 <term><varname>Type=
</varname></term>
71 <listitem><para>The GPT partition type UUID to match. This may be a GPT partition type UUID such as
72 <constant>4f68bce3-e8cd-
4db1-
96e7-fbcaf984b709
</constant>, or one of the following special
76 <title>GPT partition type identifiers
</title>
78 <tgroup cols='
2' align='left' colsep='
1' rowsep='
1'
>
79 <colspec colname=
"name" />
80 <colspec colname=
"explanation" />
84 <entry>Identifier
</entry>
85 <entry>Explanation
</entry>
91 <entry><constant>esp
</constant></entry>
92 <entry>EFI System Partition
</entry>
96 <entry><constant>xbootldr
</constant></entry>
97 <entry>Extended Boot Loader Partition
</entry>
101 <entry><constant>swap
</constant></entry>
102 <entry>Swap partition
</entry>
106 <entry><constant>home
</constant></entry>
107 <entry>Home (
<filename>/home/
</filename>) partition
</entry>
111 <entry><constant>srv
</constant></entry>
112 <entry>Server data (
<filename>/srv/
</filename>) partition
</entry>
116 <entry><constant>var
</constant></entry>
117 <entry>Variable data (
<filename>/var/
</filename>) partition
</entry>
121 <entry><constant>tmp
</constant></entry>
122 <entry>Temporary data (
<filename>/var/tmp/
</filename>) partition
</entry>
126 <entry><constant>linux-generic
</constant></entry>
127 <entry>Generic Linux file system partition
</entry>
131 <entry><constant>root
</constant></entry>
132 <entry>Root file system partition type appropriate for the local architecture (an alias for an architecture root file system partition type listed below, e.g.
<constant>root-x86-
64</constant>)
</entry>
136 <entry><constant>root-verity
</constant></entry>
137 <entry>Verity data for the root file system partition for the local architecture
</entry>
141 <entry><constant>root-secondary
</constant></entry>
142 <entry>Root file system partition of the secondary architecture of the local architecture; usually the matching
32bit architecture for the local
64bit architecture)
</entry>
146 <entry><constant>root-secondary-verity
</constant></entry>
147 <entry>Verity data for the root file system partition of the secondary architecture
</entry>
151 <entry><constant>root-x86
</constant></entry>
152 <entry>Root file system partition for the x86 (
32bit, aka i386) architecture
</entry>
156 <entry><constant>root-x86-verity
</constant></entry>
157 <entry>Verity data for the x86 (
32bit) root file system partition
</entry>
161 <entry><constant>root-x86-
64</constant></entry>
162 <entry>Root file system partition for the x86_64 (
64bit, aka amd64) architecture
</entry>
166 <entry><constant>root-x86-
64-verity
</constant></entry>
167 <entry>Verity data for the x86_64 (
64bit) root file system partition
</entry>
171 <entry><constant>root-arm
</constant></entry>
172 <entry>Root file system partition for the ARM (
32bit) architecture
</entry>
176 <entry><constant>root-arm-verity
</constant></entry>
177 <entry>Verity data for the ARM (
32bit) root file system partition
</entry>
181 <entry><constant>root-arm64
</constant></entry>
182 <entry>Root file system partition for the ARM (
64bit, aka aarch64) architecture
</entry>
186 <entry><constant>root-arm64-verity
</constant></entry>
187 <entry>Verity data for the ARM (
64bit, aka aarch64) root file system partition
</entry>
191 <entry><constant>root-ia64
</constant></entry>
192 <entry>Root file system partition for the ia64 architecture
</entry>
196 <entry><constant>root-ia64-verity
</constant></entry>
197 <entry>Verity data for the ia64 root file system partition
</entry>
203 <para>This setting defaults to
<constant>linux-generic
</constant>.
</para>
205 <para>Most of the partition type UUIDs listed above are defined in the
<ulink
206 url=
"https://systemd.io/DISCOVERABLE_PARTITIONS">Discoverable Partitions
207 Specification
</ulink>.
</para></listitem>
211 <term><varname>Label=
</varname></term>
213 <listitem><para>The textual label to assign to the partition if none is assigned yet. Note that this
214 setting is not used for matching. It is also not used when a label is already set for an existing
215 partition. It is thus only used when a partition is newly created or when an existing one had a no
216 label set (that is: an empty label). If not specified a label derived from the partition type is
217 automatically used.
</para></listitem>
221 <term><varname>UUID=
</varname></term>
223 <listitem><para>The UUID to assign to the partition if none is assigned yet. Note that this
224 setting is not used for matching. It is also not used when a UUID is already set for an existing
225 partition. It is thus only used when a partition is newly created or when an existing one had a
226 all-zero UUID set. If not specified a UUID derived from the partition type is automatically
227 used.
</para></listitem>
231 <term><varname>Priority=
</varname></term>
233 <listitem><para>A numeric priority to assign to this partition, in the range -
2147483648…
2147483647,
234 with smaller values indicating higher priority, and higher values indicating smaller priority. This
235 priority is used in case the configured size constraints on the defined partitions do not permit
236 fitting all partitions onto the available disk space. If the partitions do not fit, the highest
237 numeric partition priority of all defined partitions is determined, and all defined partitions with
238 this priority are removed from the list of new partitions to create (which may be multiple, if the
239 same priority is used for multiple partitions). The fitting algorithm is then tried again. If the
240 partitions still do not fit, the now highest numeric partition priority is determined, and the
241 matching partitions removed too, and so on. Partitions of a priority of
0 or lower are never
242 removed. If all partitions with a priority above
0 are removed and the partitions still do not fit on
243 the device the operation fails. Note that this priority has no effect on ordering partitions, for
244 that use the alphabetical order of the filenames of the partition definition files. Defaults to
249 <term><varname>Weight=
</varname></term>
251 <listitem><para>A numeric weight to assign to this partition in the range
0…
1000000. Available disk
252 space is assigned the defined partitions according to their relative weights (subject to the size
253 constraints configured with
<varname>SizeMinBytes=
</varname>,
<varname>SizeMaxBytes=
</varname>), so
254 that a partition with weight
2000 gets double the space as one with weight
1000, and a partition with
255 weight
333 a third of that. Defaults to
1000.
</para>
257 <para>The
<varname>Weight=
</varname> setting is used to distribute available disk space in an
258 "elastic" fashion, based on the disk size and existing partitions. If a partition shall have a fixed
259 size use both
<varname>SizeMinBytes=
</varname> and
<varname>SizeMaxBytes=
</varname> with the same
260 value in order to fixate the size to one value, in which case the weight has no
261 effect.
</para></listitem>
265 <term><varname>PaddingWeight=
</varname></term>
267 <listitem><para>Similar to
<varname>Weight=
</varname> but sets a weight for the free space after the
268 partition (the
"padding"). When distributing available space the weights of all partitions and all
269 defined padding is summed, and then each partition and padding gets the fraction defined by its
270 weight. Defaults to
0, i.e. by default no padding is applied.
</para>
272 <para>Padding is useful if empty space shall be left for later additions or a safety margin at the
273 end of the device or between partitions.
</para></listitem>
277 <term><varname>SizeMinBytes=
</varname></term>
278 <term><varname>SizeMaxBytes=
</varname></term>
280 <listitem><para>Specifies minimum and maximum size constraints in bytes. Takes the usual K, M, G, T,
281 … suffixes (to the base of
1024). If
<varname>SizeMinBytes=
</varname> is specified the partition is
282 created at or grown to at least the specified size. If
<varname>SizeMaxBytes=
</varname> is specified
283 the partition is created at or grown to at most the specified size. The precise size is determined
284 through the weight value value configured with
<varname>Weight=
</varname>, see above. When
285 <varname>SizeMinBytes=
</varname> is set equal to
<varname>SizeMaxBytes=
</varname> the configured
286 weight has no effect as the partition is explicitly sized to the specified fixed value. Note that
287 partitions are never created smaller than
4096 bytes, and since partitions are never shrunk the
288 previous size of the partition (in case the partition already exists) is also enforced as lower bound
289 for the new size. The values should be specified as multiples of
4096 bytes, and are rounded upwards
290 (in case of
<varname>SizeMinBytes=
</varname>) or downwards (in case of
291 <varname>SizeMaxBytes=
</varname>) otherwise. If the backing device does not provide enough space to
292 fulfill the constraints placing the partition will fail. For partitions that shall be created,
293 depending on the setting of
<varname>Priority=
</varname> (see above) the partition might be dropped
294 and the placing algorithm restarted. By default no size constraints are set.
</para></listitem>
298 <term><varname>PaddingMinBytes=
</varname></term>
299 <term><varname>PaddingMaxBytes=
</varname></term>
301 <listitem><para>Specifies minimum and maximum size constrains in bytes for the free space after the
302 partition (the
"padding"). Semantics are similar to
<varname>SizeMinBytes=
</varname> and
303 <varname>SizeMaxBytes=
</varname>, except that unlike partition sizes free space can be shrunk and can
304 be as small as zero. By default no size constraints on padding are set, so that only
305 <varname>PaddingWeight=
</varname> determines the size of the padding applied.
</para></listitem>
309 <term><varname>FactoryReset=
</varname></term>
311 <listitem><para>Takes a boolean argument. If specified the partition is marked for removal during a
312 factory reset operation. This functionality is useful to implement schemes where images can be reset
313 into their original state by removing partitions and creating them anew. Defaults to off.
</para></listitem>
319 <title>Examples
</title>
322 <title>Grow the root partition to the full disk size at first boot
</title>
324 <para>With the following file the root partition is automatically grown to the full disk if possible during boot.
</para>
326 <para><programlisting># /usr/lib/repart.d/
50-root.conf
329 </programlisting></para>
333 <title>Create a swap and home partition automatically on boot, if missing
</title>
335 <para>The home partition gets all available disk space while the swap partition gets
1G at most and
64M
336 at least. We set a priority
> 0 on the swap partition to ensure the swap partition is not used if not
337 enough space is available. For every three bytes assigned to the home partition the swap partition gets
340 <para><programlisting># /usr/lib/repart.d/
60-home.conf
343 </programlisting></para>
345 <para><programlisting># /usr/lib/repart.d/
70-swap.conf
352 </programlisting></para>
356 <title>Create B partitions in an A/B Verity setup, if missing
</title>
358 <para>Let's say the vendor intends to update OS images in an A/B setup, i.e. with two root partitions
359 (and two matching Verity partitions) that shall be used alternatingly during upgrades. To minimize
360 image sizes the original image is shipped only with one root and one Verity partition (the
"A" set),
361 and the second root and Verity partitions (the
"B" set) shall be created on first boot on the free
362 space on the medium.
</para>
364 <para><programlisting># /usr/lib/repart.d/
50-root.conf
369 </programlisting></para>
371 <para><programlisting># /usr/lib/repart.d/
60-root-verity.conf
376 </programlisting></para>
378 <para>The definitions above cover the
"A" set of root partition (of a fixed
512M size) and Verity
379 partition for the root partition (of a fixed
64M size). Let's use symlinks to create the
"B" set of
380 partitions, since after all they shall have the same properties and sizes as the
"A" set.
</para>
382 <para><programlisting># ln -s
50-root.conf /usr/lib/repart.d/
70-root-b.conf
383 # ln -s
60-root-verity.conf /usr/lib/repart.d/
80-root-verity-b.conf
384 </programlisting></para>
390 <title>See Also
</title>
392 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
393 <citerefentry><refentrytitle>systemd-repart
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
394 <citerefentry project='man-pages'
><refentrytitle>sfdisk
</refentrytitle><manvolnum>8</manvolnum></citerefentry>