Partition Clones

KIWI NG allows to create block level clones of certain partitions used in the image. Clones can be created from the root, boot and any other partition listed in the <partitions> element.

A partition clone is a simple byte dump from one block storage device to another. However, this would cause conflicts during boot of the system because all unique identifiers like the UUID of a filesystem will no longer be unique. The clone feature of KIWI NG takes care of this part and re-creates the relevant unique identifiers per cloned partition. KIWI NG allows this also for complex partitions like LVM, LUKS or RAID.

The partition clone(s) will always appear first in the partition table, followed by the origin partition. The origin partition is the one whose identifier will be referenced and used by the system. By default no cloned partition will be mounted or used by the system at boot time.

Let’s take a look at the following example:

<type image="oem" root_clone="1" boot_clone="1" firmware="uefi" filesystem="xfs" bootpartition="true" bootfilesystem="ext4">
        <partition name="home" size="10" mountpoint="/home" filesystem="ext3" clone="2"/>
    <size unit="G">100</size>

With the above setup KIWI NG will create a disk image that contains the following partition table:

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048            6143   2.0 MiB     EF02  p.legacy
   2            6144           47103   20.0 MiB    EF00  p.UEFI
   3           47104          661503   300.0 MiB   8300  p.lxbootclone1
   4          661504         1275903   300.0 MiB   8300  p.lxboot
   5         1275904         1296383   10.0 MiB    8300  p.lxhomeclone1
   6         1296384         1316863   10.0 MiB    8300  p.lxhomeclone2
   7         1316864         1337343   10.0 MiB    8300  p.lxhome
   8         1337344         3864575   2 GiB       8300  p.lxrootclone1
   9         3864576         6287326   2 GiB       8300  p.lxroot

When booting the system only the origin partitions p.lxboot, p.lxroot and p.lxhome will be mounted and visible in e.g. /etc/fstab, the bootloader or the initrd. Thus partition clones are present as a data source but are not relevant for the operating system from a functional perspective.

As shown in the above example there is one clone request for root and boot and a two clone requests for the home partition. KIWI NG does not sanity- check the provided number of clones (e.g. whether your partition table can hold that many partitions).


There is a limit how many partitions a partition table can hold. This also limits how many clones can be created.

It’s important when using the root_clone attribute to specify a size for the part of the system that represents the root partition. As of today KIWI NG does not automatically divide the root partition into two identical pieces. In order to create a clone of the partition a size specification is required. In the above example the size for root is provided via the oem-systemsize element. Using a root clone and fixed size values has the following consequences:

  1. The resize capability must be disabled. This is done via oem-resize element. The reason is that only the last partition in the partition table can be resized without destroying data. If there is a clone of the root partition it should never be resized because then the two partitions will be different in size and no longer clones of each other

  2. There can be unpartitioned space left. In the above example the overall disk size is set to 100G. The sum of all partition sizes will be smaller than this value and there is no resize available anymore. Depending on the overall size setup for the disk this will leave unpartitioned space free on the disk.

Use Case

Potential use cases for which a clone of one or more partitions is useful include among others:

Factory Resets:

Creating an image with the option to rollback to the state of the system at deployment time can be very helpful for disaster recovery

System Updates with Rollbacks e.g A/B:

Creating an image which holds extra space allowing to rollback modified data can make a system more robust. For example in a simple A/B update concept, partition A would get updated but would flip to B if A is considered broken after applying the update.


Most probably any use case based on partition clones requires additional software to manage them. KIWI NG provides the option to create the clone layout but it does not provide the software to implement the actual use case for which the partition clones are needed.

Developers writing applications based on a clone layout created with KIWI NG can leverage the metadata file /config.partids. This file is created at build time and contains the mapping between the partition name and the actual partition number in the partition table. For partition clones, the following naming convention applies:


The (name) is either taken from the name attribute of the <partition> element or it is a fixed name assigned by KIWI NG. There are the following reserved partition names for which cloning is supported:

  • root

  • readonly

  • boot

For the mentioned example this will result in the following /config.partids: