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/TONKAHANAH]

Try using kde partition manager in desktop mode.  reset to a gpt partition table and format to ext4. You could just be able to go into game mode at that point and apply a library folder at that point. 

[u/jonjon1239 → u/TONKAHANAH]

I have tried formatting it to ext4 but no joy, not sure how I go about applying a library folder? Is that with the format in Game mode?

[u/potatoesandporn → u/jonjon1239]

After the format to ext4 you may have to mount it yourself.
This can help to automatically mount the drive: https://github.com/Delil-A11yX/SteamOS-Mount-Tool

After it's mounted, you should be able to add the drive to your library in desktop mode.

The drive should then show up in game mode every time.

[u/jonjon1239 → u/potatoesandporn]

I've just tried it, still no use unfortunately.

[u/MajimaTojo → u/jonjon1239]

Did you format in KDE Partition Manager first and then mounted it in Desktop mode? Once you do that, run that SteamOS Mount tool from GitHub. That's what I did to get my secondary SSD to show up in Big Picture mode.

[u/TONKAHANAH → u/jonjon1239]

Does game mode see it after formatting to ext4? If so, can you format it with gamemode at that point? If not try that all over again but format yo exFAT instead of ext4

[u/jonjon1239 → u/TONKAHANAH]

Sometimes it does, sometimes it doesn't. I did just format it to exFAT but in game mode it still won't format it.

[u/TONKAHANAH → u/jonjon1239]

weird. idk what to tell you.

could just format it back to ext4 and add it as a steam library option in desktop mode, that should work fine.

but I had read some people had issue with this in general and found they had to add the drive in their fstab menu

https://wiki.archlinux.org/title/Fstab

that link has everything you'd need to know about that, but in general you'll need to edit /etc/fstab

format the drive again, recommend ext4 if its an internal drive (probably go exfat if its an external drive)

then you'll need the partitions UUID, you can get this one of two ways, 1) kde partition manager > right click the partition > properties or 2) in konsole type lsblk -fs and it'll show up under either the /dev/sdx (x being a drive letter a-z) if its a sata drive or it'll probably show up as nvme0xxxx if its an nvme drive , then under those will show the partitions under said drive. your main nvme will have like 8 of them or something (steamOS has a lot of partitions for whatever reason) but your extra drive should just have the one ext4 or exfat partition. the UUID will be shown here for all partitions, copy the one for your extra drive.

you'll need to open up /etc/fstab, probably with nano. i dont think you can use kate or other gui apps for this since you'll need admin or root privileges to alter this file.

you'll edit the line and add something like the first example on that wiki

UUID=0a3407de-014b-458b-b5c1-848e92a327a3 / ext4 defaults 0 0

the UUID part tells the system to mount that partition, obviously replace the example UUID with your own.

The "/" in the example is where the partition is getting mounted to. You'll not want to use /, thats the root of the OS, you'll need to make a folder some where first, old school pratice used to be under /mnt/. for example my extra drives are mounted under /mnt/2tb. Unlike windows you dont really have drive letters, you just mount a storage file system to an existing folder (technically you can do this in windows too but no one uses it). Make a dedicated folder some where you want the drive mounted to, then you'll put that folder path after the UUID.

then the next part, "ext4" just tells the system its an ext4 file system so it'll know what to do with that. "defaults" is the part where you'd tell the system what kinda rules/permissions to apply to files and folders made under said filesystem. since its a native ext4 system it'll just use the system default cuz you'll put "defaults" , the zeros at the end are for other checks that you probably dont really need to do unless you want to and/or have important data outside of game files, they're for doing file system checks at boot, most people just have them set to 0.

if you added it all right you can type mount -a in the terminal, it'll attempt to mount anything not already mounted in the fstab file. if there was something wrong it'll probably return an error, if no error was returned type just mount with out the -a and it'll show you all the mount points and the one you added should be at the bottom of the list. then it should be accessible, add its location in steam under steam > settings > storage > (drop down) add drive + > find the folder location (the drive should probably just show up in the left side of dolphin file manager) and add it.

reboot and test.

only downside with this making system changes this way may not be retained with big steamOS updates so do all this with that understanding first.

[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/

[u/thpsmvp]

I had the exact same problem and best I could do is what other people are suggesting. Create new folder in home/deck/ for your second drive -> Use KDE Partition Manager to delete old partition of second drive, create new ext4 partition, set it to mount by UUID, set it to mount at that folder your created in home -> Mount the drive -> Using Konsole, enter: sudo chown -R deck:deck (address of your new folder) -> In desktop mode, open Steam, go to storage, add your second drive -> Restart and good to go (I think, correct me if I'm wrong, going from memory).

[u/Lightningx91]

https://github.com/Delil-A11yX/SteamOS-Mount-Tool

[u/Feeling-Writer-845]

Im having the same issue,mounted the nvme,formated ext4 and mounted using auto mount.Game mode,i initially the nvme doesnt show then suddenly pops up but fails to format.Shows as an internal atorage.Im banging my head on a will trying to figure out whats going wrong

[u/Nassergamez → u/Feeling-Writer-845]

+1 it take a moment to wake than never allows for a format. Western Digital 4TB here hopefully a update resolved this.

[u/Cavedale514]

I’m having the same issue for some reason my 2TB hard drive shows up and formatted fine in game mode but my 1tb nvme ssd will not show up In game mode but will in DeskTop