My instructions for bitcoin node with a secondary ssd to install umbrel (I have proxmox in a minipc (n100) with nvme 1tb and secondary hard drive of 2tb):
Connect the secondary hard drive in Proxmox, it will appear in the disks section. It won’t have any partitions if it is new. First, ‘wipe disk’ if it wasn’t clean, second, ‘initialize disk with GPT’. Third (optional), partition it. In my case, I had a new 2TB SSD and wanted to use 1TB for Umbrel. So, accessing Proxmox’s shell, we run the command ‘fdisk /dev/sda’ and follow the instructions (in my case, create two partitions).
Once created, they appear as /dev/sda1 and /dev/sda2. Now we create a Directory or LVM from the partition I will use, so when we create the VM of Ubuntu or Debian (or CT) for Proxmox we can choose this partition of the secondary hard drive as storage (and not the main drive that Proxmox uses). In my case, under the LVM tab, ‘create: volume group’: 'disk: /dev/sda1 and a ‘name’, then create. It now appears as available storage. Now you can create the VM or CT of Ubuntu or Debian (in my case Debian VM) choosing that storage (1TB). Once with Debian or Ubuntu installed, install Umbrel.
Other possibility: 2 devices (main for linux os and secondary for umbrel 1tb): It would be possible to create the Debian/Ubuntu VM (or CT) with two disks (the main one where to install Debian or Ubuntu using part of the main Proxmox local lvm (for example 32gb) and the secondary one (1tb) for Umbrel. In that case when executing the installation command of Umbrel: you have to define the path ‘curl -L https://umbrel.sh | bash -s – --install-path /some/path’ (replacing ‘/some/path’ with the path of your directory)
Hope this helps someone out there!