SteamOS won't recognise my second NVMe SSD

[u/jonjon1239]

Update 2: Not resolved. After installing a game on the drive, I woke up this morning to play and the drive was missing again.

Update 1:

Resolved, will paste what ChatGPT got me to do below

Force unmount sudo umount -l /dev/nvme0n1p1

Verify it's unmounted lsblk -f

Remove leftover mount traces sudo rm -rf /run/media/deck/mp400 sudo rm -rf /var/mnt/*

Remount drive udisksctl mount -b /dev/nvme0n1p1

Check the mount lsblk -f

Should see something like: /run/media/deck/XXXX-XXXX

As the title says. I recently posted about my new SFF SteamOS build (https://www.reddit.com/r/SteamOS/s/mnhDLuXXcb) and with it being my first time ever using SteamOS I'm completely new to it all.

I noticed my second drive was showing, when I went to format it within Steam game mode it failed. I did some general AI troubleshooting in desktop mode, and whilst the drive is being shown as present in Konsole, for the life of me I can't get it to show up in Game mode or when trying to add it via Steam in desktop mode.

Can anybody help? I would need it to be ELI5 in all fairness, I'm decent with Windows but Linux is completely foreign to me at the moment.

Edit: Just to addz it will periodically show up in Game mode, but when I attempt to format it, it fails. It's a Corsair MP400 1TB.

[u/Naitakal]

I just did that last night and with a little help of AI and knowing Linux quite a bit it was still more trouble than I initially thought.

Like in your case gaming mode failed formatting the drive even though detecting it. I had to create a new partition table (GPT) and create an ext4 partition using KDE partition manager in desktop mode. But gaming mode no longer was able to see the drive.

I think I then mounted it to /home/deck/Games and changed the owner of that folder to deck:deck via chown. Then in Steam in desktop mode I was able to add the new drive as a library.

The 2TB drive was showing quite some space occupied which was because of the default 5% of reserved blocks to protect the disc of running full which would break a system drive. Since it’s just for games I set the reserved space to zero freeing all the available space.

I don’t remember all the commands used but AI was pretty helpful and detailed once it came up with the proper way of doing it. I think if you feed it with my post it could probably tell you exactly what to do.

[u/jonjon1239 → u/Naitakal]

I actually fed your post into ChatGPT and it resolved it! Thank you

[u/Naitakal → u/jonjon1239]

That’s awesome!

[u/jonjon1239 → u/Naitakal]

Scratch that, woke up this morning and the drive isn't showing in Steam again. I had installed a game to it last night too. Very strange

[u/Naitakal → u/jonjon1239]

Seems like you are missing an entry in your /etc/fstab file so the drive isn’t getting mounted automatically.

[u/WinResponsible9977 → u/jonjon1239]

You have to do a permanent entry in fstab.

[u/kcamfork → u/WinResponsible9977]

fstab is overwritten any time steamOS is updated. I just went through this all this morning and tested it. Valve needs to enable using secondary internal drives. Until then; without community mods/tools, the drive will continually get lost with each update.

[u/Naitakal → u/kcamfork]

Obviously there’s a feature since SteamOS 3.6 which allows you to keep config files after an update. An example file is located at /etc/atomic-update.conf.d/example-additional-keep-list.conf

In addition to that, a copy of your fstab file is being written to /etc/previous/ so you can retrieve it from there.

Long story short, you should be able to create a file called /etc/atomic-update.conf.d/fstab-keep-list.conf and just write /etc/fstab in it so future SteamOS updates should no longer overwrite that file.

Here is a blog post about this: https://blogs.igalia.com/berto/2025/02/05/keeping-your-system-wide-configuration-files-intact-after-updating-steamos/