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theme seriph
background https://cover.sli.dev
title Reproducible Linux Installations on Your Laptop Without Data Loss
info Holger Fischer (hoo) - hoonetorg - 2026
class text-center
transition fade-out
duration 1h

Reproducible Linux Installations

on Your Laptop Without Data Loss

...or having multiple Linux installs side-by-side

...or switching Linux distributions without hassle

Holger Fischer (hoo) - hoonetorg - 2026

The Problem

The installer has a lot of capabilities, but it's dangerous if you don't know exactly what you are doing.

Modern OS installers are great at first installs on empty disks.

Most have an interactive partition editor,

but:

One wrong click and your data is gone - like that.

It's not the installer's fault. It's

  • that humans make mistakes under pressure, at 2am, or
  • simply because the layout wasn't obvious.

Many colleagues told me they accidentally wiped their data on (re)install.

Many reports on the internet where you can read

"I lost my data on (re)install, even when I tried hard to keep it"

The Strategy: Know Your Disk State

Two modes — decided by what's already on disk:

Situation Layout
Empty disk / single OS planned single-os
Existing OS(es) detected multi-os

A Python pre-script inspects the real partition table before touching anything.

It aborts if the state doesn't match expectations. - No guessing. No silent data loss.

BUT:

Have you defined your disk layout correctly - otherwise data loss

TEST before you install on real hardware

!!! HAVE BACKUPS !!!

layout: two-cols

Disk Layout: Multi-OS Example

1  EFI                 <- preserved, reused
2  MS Reserved         <- untouched
3  Windows             <- untouched
4  WinRecovery         <- untouched
--------- startpartition 5 -----------------------------
5  /boot               <- created or emptied
6  OS                  <- created or emptied
   (LUKS, btrfs)         
   subvol: root
   subvol: home
--------------------------------------------------------
7  data                <- never touched on OS install
   (LUKS, btrfs)          created or verified by Ansible
   subvol: holger      -> /home/holger
   subvol: images      -> /var/lib/libvirt/images

8  winexchange         -> exchange data between
   (NTFS, unencrypted)    Windows and Linux

::right::

Rules

  • Partitions 1–4: never touched

  • Partitions 5+6: created on first install, emptied on reinstall

  • Partitions after 6: never touched

    Ansible creates or verifies the state of these partitions

  • EFI is reused → other OSes keep booting

  • Distribution swap on reinstall: possible


Ubuntu → Fedora on same partitions. Windows and data: untouched.

Partition Layout:

4 TB disk - P7 ≈ 3490 GiB

Fixed partitions total: 606 GiB. Scale: each `=` ≈ 82 GiB
 
| Part | Size       | Bar                                 
|------|------------|--------------------------------------------
| 1    | 2 GiB      | =                                                  
| 2    | 256 MiB    | =                                                  
| 3    | 200 GiB    | ==                                                 
| 4    | 2 GiB      | =                                                  
| 5    | 2 GiB      | =
| 6    | 200 GiB    | ==
| 7    | ~3490 GiB  | ===========================================        
| 8    | 200 GiB    | ==

1TB disk, 2TB disk and 4TB disk in relation

1TB: |1|2|  3 (200G)  |4|5|  6 (200G)  |        7 (~418G)        |  8 (200G)  |

2TB: |1|2| 3G |4|5| 6G |               7 (~1442G)               | 8G |

4TB: |1|2|3G|4|5|6G|                       7 (~3490G)                       |8G|

The Builders (1)

Everything runs in Podman containers. No special host setup beyond: podman · tar · rsync - gpg


faibuilder / ksbuilder

faibuilder: produces a bootable disk image (btrfs, thumbdrive-ready) with the installer (FAI-based)

ksbuilder: produces a an image with a partition labeled "OEMDRV" which is found by the second connected image containing a standard Fedora/RHEL (and similar) ISO image.

Both builders add an additional partition labeled "EXTRA" for additional content:

  • Ansible content (encrypted)
  • Offline package repos (e.g. Fedora 43 WS — no Anaconda ISO exists, only LIVE ISO)
  • Whatever you need

Installations run fully offline. No internet required.


The Builders (2)

Everything runs in Podman containers. No special host setup beyond: podman · tar · rsync - gpg

nsbldr (Ansible builder)

Packages Ansible content into a GPG-symmetrically encrypted archive.

Extracted after first boot → run via a dedicated system user (f.e. hoo).

Archive can contains:

  • Ansible inventories
  • Ansible files (files that should be delivered statically or via template)
  • Ansible playbooks
  • Ansible roles
  • Ansible collections

The Full Workflow

 faibuilder                          nsbldr
 or ksbuilder                        (Ansible builder)
      |                                    |
      v                                    v
 Thumbdrive image                  Encrypted ansible tar
      |                                    |
      v                                    |
 Install / Reinstall                       |
 (pre-script verifies disk state)          |
      |                                    |
      v                                    v
 First boot  <--------------------------  import & run ansible
                                           |
                                           v
                                    verify/create data subvols
                                    mountpoints + permissions
                                    create local users

layout: center class: text-center

Live Demo

First install → Reinstall with a Distribution swap

Windows and data: untouched throughout



Ask questions while it runs — installs take a few minutes

layout: center class: text-center

Takeaways & Links

Even if your setup looks nothing like mine — steal what's useful:

  • LUKS + Btrfs subvolumes as a sane data/OS separation
  • Pre-script state verification before any destructive action
  • Offline-first installer images via Podman
  • Agama support: work in progress

hoonetorg · github.com/hoonetorg

Slides + code links:

Slides

Source code:

Watch out for existing repos and changes at github.com/hoonetorg.

There will be a repo (not named yet) consolidating all required tools, containing examples.

Holger Fischer (hoo) - hoonetorg - 2026