Steam Deck Windows on A2 Micro SD Card help needed

[Vision541]

So i know how to get windows on my 1tb sd card, Once I install it on there, I want to use half for steam os games and half for windows games. If I create a new partition in windows, do I need to do anythng within steam os? I have the 64gb model so not much to work with. Im wondering If i hit format sd card will it remove everything including the windows install?

[retrogunner]

I've not done what you are attempting. This is from my different experiences mashed together to help provide some guiderails.

On the Steam Deck, it has Menu > System > KDE Partition manager. ( I'm used to using GParted.) You'll like want to confirm how to do a partition resize in KDE (there's a button for it.)

You should be able to resize down the Windows partition. With GParted, it will move any necessary data. I assume KDE's will do the same.

Afterwards, it will leave behind unused storage.

Make a new partition there. It will likely need to be formatted NTFS if you wish to use any games there in both on Windows and Steam OS. Again, you'll need to research the best approach to having a shared game space.

My suspicion is that you may need to create "SteamLibrary" directory on it by installing a super small game from the Steam OS side. (You'll need to muck around with Settings > Storage to add the volume.) You might even be better off doing that from Desktop Mode using the Steam Client in "normal'ish" mode.

On the Windows side, in Steam, you'll need do add the volume (it would be identical to doing it in Linux Desktop mode client.)

After that, you should be good.

You'll likely want to make sure any games you install are Windows only. SteamOS might install their Linux version.

And you might need to always install them via SteamOS so it creates the necessary PREFIX. WIndows should still find and use them on the shared SteamLibrary directory. If you're only going to use Windows exclusive games (i.e. Destiny 2) well, install those in Windows so you're not Banned.

Be aware, Steam OS tends to create the PREFIX directories under /home/deck/.local/steam so you will need free space on your internal storage for those and the shader cache as well. Shader cache can be 5-10% the game install size -- especially for shooters.

Please consider posting a howto of your successful steps on both here and Reddit's r/SteamDeck (and/or r/SteamDeckTricks )

Cheers, retro.