ReaR version

Relax-and-Recover 2.9 / 2025-02-13

Describe the ReaR bug in detail

I am using a guide (https://abbbi.github.io/hetzner/)
to migrate a Digitalocean droplet to a Hetzner VPS
using ReaR and kexec.

I am not 100% sure that the rescue media is being created correctly.

Here is the output from running, "sudo rear mkrescue -d"
(on the Digitalocean droplet):

Relax-and-Recover 2.9 / 2025-02-13
Running rear mkrescue (PID 370982 date 2026-03-23 22:20:11)
Command line options: /usr/sbin/rear mkrescue -d
Using log file: /var/log/rear/rear-vps1.log
Using build area: /var/tmp/rear.L0LpN1mL3kJs0Bw
Setting TMPDIR to ReaR's '/var/tmp/rear.L0LpN1mL3kJs0Bw/tmp' (was unset when ReaR was launched)
Running 'init' stage ======================
Running workflow mkrescue on the normal/original system
Running 'prep' stage ======================
Using '/usr/bin/xorrisofs' to create ISO filesystem images
Secure Boot is not supported, not using Secure Boot shim:
EFI variables are not supported on this system
Using autodetected kernel '/boot/vmlinuz-6.8.0-106-generic' as kernel in the recovery system
Modified ReaR recovery system area after 'prep' stage (/var/tmp/rear.L0LpN1mL3kJs0Bw/rootfs contains regular files)
Running 'layout/save' stage ======================
Creating disk layout
Overwriting existing disk layout file /var/lib/rear/layout/disklayout.conf
Disabling excluded components in /var/lib/rear/layout/disklayout.conf
GRUB found in first bytes on /dev/vda and GRUB 2 is installed, using GRUB2 as a guessed bootloader for 'rear recover'
Skip saving storage layout as 'barrel' devicegraph (no 'barrel' command)
Verifying that the entries in /var/lib/rear/layout/disklayout.conf are correct
Created disk layout (check the results in /var/lib/rear/layout/disklayout.conf)
Running 'rescue' stage ======================
Creating recovery system root filesystem skeleton layout
Adding 'console=tty1' to KERNEL_CMDLINE
Adding 'console=ttyS0' to KERNEL_CMDLINE
Handling network interface 'eth0'
eth0 is a physical device
Handled network interface 'eth0'
Handling network interface 'eth1'
eth1 is a physical device
Handled network interface 'eth1'
Skipping 'lo': not bound to any physical interface.
Included current keyboard mapping (via 'dumpkeys -f')
No default US keyboard mapping included (no KEYMAPS_DEFAULT_DIRECTORY specified)
No support for different keyboard layouts (neither KEYMAPS_DEFAULT_DIRECTORY nor KEYMAPS_DIRECTORIES specified)
Copying logfile /var/log/rear/rear-vps1.log into initramfs as '/tmp/rear-vps1-partial-2026-03-23T22:20:19+00:00.log'
Running 'build' stage ======================
Copying files and directories
Copying binaries and libraries
Copying all kernel modules in /lib/modules/6.8.0-106-generic (MODULES contains 'all_modules')
Failed to copy all contents of /lib/modules/6.8.0-106-generic (dangling symlinks could be a reason)
Copying all files in /lib*/firmware/
Skip copying broken symlink '/etc/resolv.conf' target '/run/systemd/resolve/stub-resolv.conf' on /proc/ /sys/ /dev/ or /run/
Skip copying broken symlink '/etc/mtab' target '/proc/379878/mounts' on /proc/ /sys/ /dev/ or /run/
Testing that the ReaR recovery system in '/var/tmp/rear.L0LpN1mL3kJs0Bw/rootfs' contains a usable system
Testing each binary with 'ldd' for 'not found' libraries within the ReaR recovery system
Testing that the existing programs in the PROGS array can be found as executable command within the ReaR recovery system
Testing that each program in the REQUIRED_PROGS array can be found as executable command within the ReaR recovery system
Running 'pack' stage ======================
Creating recovery/rescue system initramfs/initrd initrd.cgz with gzip default compression
Created initrd.cgz with gzip default compression (792 MiB) in 60 seconds
Running 'output' stage ======================
Making ISO image
Wrote ISO image: /var/lib/rear/output/rear-vps1.iso (810M)
Exiting rear mkrescue (PID 370982) and its descendant processes ...
Running exit tasks
To remove the build area you may use (with caution): rm -Rf --one-file-system /var/tmp/rear.L0LpN1mL3kJs0Bw

There is an error in output of the above command,
but I am unsure if it is causing the rescue media to fail to boot..

The error in the debug output is:

Failed to copy all contents of /lib/modules/6.8.0-106-generic (dangling symlinks could be a reason)

FYI:

Running "sudo rear mkrescue -d" does produce an ISO.

The rescue media is booted from a running Hetzner VPS
using the following command:

kexec --initrd /tmp2/initrd.cgz --command-line="consoleblank=0 systemd.show_status=true console=tty1 console=ttyS0" /tmp2/kernel

Running Kexec does result in the VPS rebooting and
running the kernel and initrd from rescue media;
however the rescue media hangs at the following point:

[ 4.780612] clk: Disabling unused clocks
[ 4.788480] Freeing unused decrypted memory: 2028K
[ 4.792429] Freeing unused kernel image (initmem) memory: 4920K
[ 4.808866] Write protecting the kernel read-only data: 38912k
[ 4.813574] Freeing unused kernel image (rodata/data gap) memory: 1976K
[ 4.869100] x86/mm: Checked W+X mappings: passed, no W+X pages found.
[ 4.870673] Run /init as init process
[ 4.878758] systemd[1]: Inserted module 'autofs4'
[ 4.903531] systemd[1]: systemd 255.4-1ubuntu8.12 running in system mode (+PA
M +AUDIT +SELINUX +APPARMOR +IMA +SMACK +SECCOMP +GCRYPT -GNUTLS +OPENSSL +ACL +
BLKID +CURL +ELFUTILS +FIDO2 +IDN2 -IDN +IPTC +KMOD +LIBCRYPTSETUP +LIBFDISK +PC
RE2 -PWQUALITY +P11KIT +QRENCODE +TPM2 +BZIP2 +LZ4 +XZ +ZLIB +ZSTD -BPF_FRAMEWOR
K -XKBCOMMON +UTMP +SYSVINIT default-hierarchy=unified)
[ 4.919813] systemd[1]: Detected virtualization kvm.
[ 4.922871] systemd[1]: Detected architecture x86-64.
[ 4.925923] systemd[1]: Detected first boot.
[ 4.931667] systemd[1]: Hostname set to .
[ 4.934933] systemd[1]: Initializing machine ID from VM UUID.
[ 4.968610] systemd[1]: /usr/lib/systemd/system/[email protected]:46: Failed to
resolve instance name in DefaultInstance="%I": Invalid slot
[ 4.983474] systemd[1]: /usr/lib/systemd/system/[email protected]:46: Failed to
resolve instance name in DefaultInstance="%I": Invalid slot
[ 4.987690] systemd[1]: Failed to populate /etc with preset unit settings, ig
noring: Invalid slot

Platform

Linux x64

OS version

"Ubuntu 24.04.4 LTS"

Backup

No response

Storage layout

NAME         KNAME      PKNAME   TRAN   TYPE FSTYPE   LABEL            SIZE MOUNTPOINT
/dev/loop0   /dev/loop0                 loop squashfs                 55.5M /snap/core18/2979
/dev/loop1   /dev/loop1                 loop squashfs                 55.5M /snap/core18/2999
/dev/loop3   /dev/loop3                 loop squashfs                 63.8M /snap/core20/2717
/dev/loop4   /dev/loop4                 loop squashfs                 91.9M /snap/lxd/36554
/dev/loop5   /dev/loop5                 loop squashfs                 63.8M /snap/core20/2769
/dev/loop6   /dev/loop6                 loop squashfs                 91.9M /snap/lxd/38333
/dev/loop7   /dev/loop7                 loop squashfs                 48.1M /snap/snapd/25935
/dev/loop8   /dev/loop8                 loop squashfs                 48.4M /snap/snapd/26382
/dev/vda     /dev/vda            virtio disk                            25G 
|-/dev/vda1  /dev/vda1  /dev/vda virtio part ext4     cloudimg-rootfs 24.9G /
|-/dev/vda14 /dev/vda14 /dev/vda virtio part                             4M 
`-/dev/vda15 /dev/vda15 /dev/vda virtio part vfat     UEFI             106M /boot/efi

What steps will reproduce the bug?

Run sudo rear mkrescue -d on a 1 vCPU 1GB Digtalocean Droplet.
Then run

kexec --initrd /tmp2/initrd.cgz --command-line="consoleblank=0 systemd.show_status=true console=tty1 console=ttyS0" /tmp2/kernel

on a "cx23" VPS on Hetzner running "Ubuntu 24.04.4 LTS".

Workaround, if any

No response