Short answer: keep Ubuntu Server and add CasaOS if you already depend on normal Linux package management, systemd services, custom networking, or host-level tools. Replace it with ZimaOS if you want the machine to behave more like a dedicated NAS appliance and most workloads can live inside the app/container model.
CasaOS sits on top of Linux
CasaOS installs onto an existing distribution. Current CasaOS system support lists Debian 12 as recommended and Ubuntu Server among tested options. The one-line installer adds CasaOS without replacing the base OS.
That makes Ubuntu + CasaOS the flexible choice when you still use apt, custom systemd units, host VPNs, native game-server packages, monitoring agents, or scripts that assume a conventional Linux server.
ZimaOS replaces the host OS
ZimaOS is installed as a bootable operating-system image. Current ZimaOS x86 installation targets generic x86-64, requires UEFI boot, Secure Boot disabled, and at least 25GB of storage.
This model fits a machine whose main job is storage, Jellyfin, backups, Docker apps, and other home-server services. You trade some host-level freedom for a more appliance-like workflow.
Use the workload to decide
| Need | Better starting point | Why |
|---|---|---|
| Jellyfin + a few containers | ZimaOS | Less host administration. |
| Jellyfin + native Linux tools | Ubuntu + CasaOS | Keeps normal Linux control. |
| Game servers with custom scripts | Ubuntu + CasaOS | Easier host-level dependencies. |
| Mostly NAS/media/backup | ZimaOS | Purpose-built appliance model. |
Do not erase Ubuntu before inventorying state
Before replacing the OS, record Docker compose files, environment variables, bind mounts, /DATA/AppData, media paths, game saves, PUID/PGID ownership, static IP/DNS, reverse proxy, VPN, firewall rules, and hardware-transcoding device mappings.
An OS change does not automatically preserve Jellyfin libraries or game data, and it does not guarantee GPU transcoding on unsupported hardware.
Decision rule
Keep Ubuntu + CasaOS when the box is still a Linux server first and a NAS dashboard second. Choose ZimaOS when it is a home server/NAS first and most workloads fit containers and built-in storage workflows.
The CasaOS Docker model shows why CasaOS works well as a visual layer over Linux. The ZimaOS app platform shows the appliance-style alternative.
If you are building a dedicated x86 home server rather than repurposing an existing machine, ZimaBoard 2 supports both approaches.
Think about updates and recovery, not just installation
Ubuntu + CasaOS gives you two update layers: the Linux distribution and CasaOS itself. That is useful when you want to pin packages or manage kernel changes, but you also own more compatibility work. ZimaOS treats the machine more like an appliance, so the system lifecycle is simpler but intentionally less like a general-purpose Debian host.
If you already have a stable Ubuntu server, the lowest-risk test is to install CasaOS without deleting anything important, add one non-critical app, and see whether the workflow fits. Moving to ZimaOS is a bigger decision because it changes the host OS and therefore should be tested with a verified backup and recovery path.
For Jellyfin, preserve four things
- Media paths: keep the same host folders or update the container mappings.
- Jellyfin config: preserve the application's config/database directory, not just the movie files.
- GPU devices: record Intel/AMD/NVIDIA device mappings and driver assumptions before migration.
- Ports and reverse proxy: note whether clients reach Jellyfin by LAN IP, hostname, or public domain.
A fresh install that can “see the movies” is not equivalent to a successful Jellyfin migration if watch history, users, artwork, or transcoding settings disappear.
Game servers make host flexibility more valuable
Many game servers fit Docker well, but mod loaders, SteamCMD scripts, Wine/Proton dependencies, firewall exceptions, or custom startup logic can be easier on a conventional Linux host. If your game server is already stable on Ubuntu, keeping Ubuntu and adding CasaOS avoids turning an unrelated working service into a migration project.
Conversely, if all game servers are already containerized and their data is bind-mounted cleanly, ZimaOS becomes easier to evaluate because the workload is portable.
Run a portability test before deciding
For each important service, answer these five questions:
- Where is its persistent data?
- Can I recreate the container from a compose file?
- Does it need host packages outside Docker?
- Does it need special hardware devices?
- Can I restore it on a clean machine from backup?
If you cannot answer those questions, changing the host OS is premature. Build the backup/restore path first; the operating-system choice becomes much easier after the workloads are portable.
FAQ
Does CasaOS replace Ubuntu?
No. CasaOS installs on top of a supported Linux system.
Does ZimaOS replace the system disk?
A normal ZimaOS installation writes a dedicated OS image to a target disk, so back up that disk first.
