How to properly map users and groups across Proxmox LXC and Docker VM for shared media folders?

schrackin

New Member
Jan 10, 2026
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Hi everyone,

I just started learning Proxmox VE, so please be kind with me.

I recently bought a Ugreen DXP2800 NAS (8GB RAM, 512GB M.2 SSD, 8TB SATA HDD) for my home server. I successfully moved HomeAssistant from my NUC to a VM on Proxmox, but I’m struggling to move my Samba file server and ARR stack to Proxmox.

Here’s what I have done so far:

Formatted the HDD to ext4, mounted it on the node, and copied 4TB of media files and documents from my USB HDD.

Installed a Debian 12 unprivileged LXC with Cockpit and Samba to share files over my network and provide a Time Machine backup target for my Mac.

Installed a Docker VM for my ARR stack using Proxmox helper scripts.

I’m confused about the proper way to create and map users and groups across the Proxmox host, LXC, and Docker VM, so that the media and backup folders can be shared without UID/GID conflicts.

I’ve read these blog posts:

Proxmox ZFS mounts and id mapping: https://blog.kye.dev/proxmox-zfs-mounts

Tips for idmap in unprivileged LXC: https://www.apalrd.net/posts/2023/tip_idmap/

…but I still don’t fully understand the best approach.

My plan is to create separate users and relevant groups for:

media, backup, tm-backup, containers, myself

Here’s my file server LXC config (/etc/pve/lxc/102.conf):

Code:
arch: amd64
cores: 2
features: nesting=1
hostname: fileserver
memory: 512
mp1: /mnt/shdd1/media/,mp=/mnt/media,size=5T
mp2: /mnt/shdd1/backup-timemachine/,mp=/mnt/backup-timemachine,size=500G
net0: name=eth0,bridge=vmbr0,firewall=1,gw=192.168.0.254,hwaddr=x,ip=192.168.0.6>
net1: name=eth1,bridge=vmbr0,firewall=1,gw=192.168.0.254,hwaddr=x,ip=192.168.0.7>
ostype: debian
rootfs: local:102/vm-102-disk-0.raw,size=8G
swap: 512
unprivileged: 1

Folder structure on the host:

Code:
/mnt/shdd1/
├── backup-files
│ ├── containers
│ └── homeassistant
├── backup-timemachine
│ └── Laptop.sparsebundle
├── documents
│ └── docs
├── downloads
│ ├── books
│ ├── movies
│ ├── music
│ ├── qbittorrent
│ ├── tv
│ └── ytdl
├── media
│ ├── books
│ ├── movies
│ ├── music
│ ├── syncthing
│ ├── tv
│ └── videos

How should I properly map users and groups across the Proxmox host, LXC, and Docker VM, so that all these folders are shared correctly and safely, without running into UID/GID conflicts?

Thanks in advance for any guidance!