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How to Add an External SSD to Your Steam Deck

Written by: Goran Damjanovic
How to add External SSD HDD Steam Deck Autoboot

Expanding the storage of Valve’s handheld console can be done in several ways; the easier route would be to just purchase a Steam Deck SD Card, where Glenn concluded that the SanDisk Extreme series is your best bet. The DIY solution, with some elbow grease, would be to upgrade the internal Steam Deck SSD by yourself, which might or might not be complicated, depending on your skill level. The middle route, probably best for those not comfortable with opening their console, would be to take your old/new hard drive and just plug it in to the Steam Deck, with a caveat though.

In our article on the best SSD for Steam Deck we mentioned that the procedure of adding an external SSD or HDD takes a few extra steps to make it work, and in this guide we’re going to explain you exactly what you need to do.

For easier copy/pasting action, we recommend opening this guide on your Steam Deck.

Friendly Advice: Arm Yourself With a Keyboard and Mouse

While, technically, you can add an external SSD to your Steam Deck by using the touchscreen and on-screen keyboard, we highly recommend using a keyboard and mouse. There’s pasting and saving stuff with keyboard shortcuts, and a mouse is of great help for selecting and copying text.

For this exercise, you can either connect the keyboard and mouse through Bluetooth, the official Steam Deck Dock, or get one of the many Steam Deck Dock alternatives – completely up to you.

You don’t need an external keyboard and mouse, but it will definitely make the process easier.

Now Boot into Desktop Mode and Create a Sudo Password

Before you hook your SSD/HDD to your Steam Deck, you must boot into Desktop Mode and create a Sudo password. If you already have a Sudo password set, skip this step.

To boot into Desktop mode, press the Steam button, select the Power menu (the one at the bottom) and enter it by pressing the A button, and then select the Switch to Desktop option and press the A button again.

After you enter Desktop Mode, create a Sudo password that you’ll need to enter multiple times during the process of adding the external SSD to your Steam Deck. If you already have it set, skip this step.

Now open Konsole, the app used to enter Linux commands, by clicking the Application Launcher button (the button on the lower left part of the Desktop), the System tab, and then the Konsole button.

How to Open Konsole on Steam Deck

Now type “passwd” without the brackets, after that type in your password, press the Enter key, confirm it by entering the password again, and then close Konsole.

How to Open Konsole on Steam Deck 2

Move on to SSD/HDD Formatting and Mounting

Here’s the part where we will mount the external drive to the Steam Deck and format it, so that the console can read it properly. It’s important to note that formatting process is deleting all of the data on that specific drive, so if you need to do a backup, now is the best time to do it.

Mount the SSD by hooking it to your Deck, clicking the removable drives button, and then clicking the Mount and Open button, like in the screenshot below.

Mount the SSD by hooking it to your Deck

Now it’s time to format the external drive, you can do so by opening the KDE Partition Manager, click on the Application Launcher -> System -> KDE Partition Manager.

Now format the external drive

Enter your sudo password and delete the old partitions. You need to enter your sudo password each time you launch KDE Partition Manager. Once you enter the password, select every partition found on the external SSD, right-click it, and then click on the Delete button. In our case we have several partitions, you might only have one.

delete the old partitions

Once you finish, click on the unallocated tab (it should be the only tab available if you’ve deleted every partition) and select the New button.

Repeat the action for each partition

Now create a Steam Deck compatible partition. When doing so, make sure to pick the ext4 file system in the options and label the new partition under an easily recognizable name. As you can see below, we named the partition “ExtSSD.” Once you set it all up, click the OK button and then click the Apply button found on the upper left side of the KDE Partition Manager window.

How To Add External SSD to Steam Deck 07

The app will now first delete old partitions and then create the new one. Once it notifies you that it has successfully finished all tasks, click the OK button and exit.

How To Add External HDD to Steam Deck 08

Change Read and Write Permissions

The next step is switching read and write permissions on the SSD from root to Deck, allowing Steam, and other apps on your Steam Deck, to automatically read and write data on the SSD. In other words, allowing Steam to install games on the drive.

Be super careful about spaces! If you don’t include a space where needed or have one where it shouldn’t be, Konsole won’t recognize the command, and you’ll have to do it all again.

To change read and write permissions, open Konsole again and then type the following:

cd /run/media/deck

Once you type the command, press Enter, and then type:


That’s a lowercase L. The ls command will list your external SSD’s label. Copy the label and then type the following command:

sudo chown Deck your SSD label

In our case, the command looks like this:

sudo chown deck ExtSSD

Press Enter, type your sudo password when prompted, and then press Enter again.

Add External SSD to Steam Deck 09

The read and write permissions should be switched if you did it right. To check this, open the Dolphin file manager, locate the Removable Storage tab (should be located at the bottom), right-click on your external SSD, and click the Properties tab.

Add External HDD to Steam Deck 10

Once inside the Properties tab, click the Permissions tab, and you should see User: deck under the Ownership tab. If it says root (ignore the Group option, just focus on the User), repeat the Konsole procedure listed above. If you see that the ownership is switched to Deck, great, you’re pretty much done.

How To Add External SSD to Steam Deck 11

Add the External SSD to Steam as a Steam Library Folder

This is the last step in the process, here you’ll need to add the external SSD as a Steam Library folder. This is super straightforward.

First, open Steam in Desktop Mode, click on the Steam button, and then click on Settings.

How To Add External SSD to Steam Deck 16

Then select the Downloads tab, and click on the Steam Library Folders button.

Adding an external SSD to Steam Deck 17

Press the Plus sign, this will list out the available options.

How To Add External SSD to Steam Deck 18

Select your SSD, by clicking on the add button.

How To Add External SSD to Steam Deck 19

That’s it!

How To Add External SSD to Steam Deck 20

Ok, Now What? How Do I Use the External Drive?

Same as you would use an SD Card, you can download games to your external drive and play from it – but with some additional steps if you want to make the experience as flawless as the internal drive one.

The issue with external drives for the Steam Deck is the following – every time you reboot your deck, or disconnect the drive when in game mode, you would need to mount your external drive again by following the above process – which can be a chore.

The good news is that there’s a solution to it, the bad news is that the same solution has a mind of its own – sometimes it works, sometimes it doesn’t, and it can potentially mess up your console.

Let us elaborate.

Enabling Automatic SSD Mounting Doesn’t Work Great

From our experience, enabling the automatic SSD mounting option didn’t lead to the external SSD being automatically mounted every time, especially in Game Mode.

For example, rebooting into Game Mode with the SSD attached worked perfectly in the sense that Steam would automatically recognize the SSD. Hooking the SSD to our Deck in Game Mode for the first time after a reboot, after we rebooted our Deck without the SSD attached, would also automatically mount it every single time.

On the other hand, after physically disconnecting the drive and then hooking it up again while in Game Mode, the SSD wouldn’t mount and show in the storage menu.

We had to switch to Desktop Mode and manually add it as a games folder via Steam to use it in Game Mode, or just start any game installed on it while in Desktop Mode by clicking its icon on the desktop. This would lead to SteamOS automatically adding the SSD as a Steam folder. Starting a game in Game Mode to make SteamOS mount the SSD, however, didn’t work since the only option there was to download the game on our internal SSD.

In Desktop Mode, unhooking the drive and then reconnecting it led to SteamOS automatically mounting it each and every time. But yeah, in Game Mode, the SSD would be recognized only after connecting it for the first time after a reboot.

And yes, we tried enabling the Automount Device option found in Disk and Devices settings to remedy the issue, but it didn’t work. Enabling the option would only lead to SteamOS asking for the sudo password to mount the external SSD each time we switched to Desktop Mode.

Note that some Steam Deck owners have reported that automatic SSD mounting works perfectly for them, while others had the same issues as we did, so your mileage may vary. If we had to guess why this procedure doesn’t work as supposed to, we’d assume Valve enabling automatic mount of ext4 external drives in the SteamOS 3.4 update and then immediately disabling the feature in the 3.4.1 update just a few days later somehow messed up the feature after you enable it manually via Konsole.

How to Enable Automatic SSD Mounting After Reboot

Ok, you’ve decided to enable automatic SSD mounting, but before you do, let us place some big red letters:

If you mess anything up during the procedure, you might end with an infinite boot the next time you restart your Deck. 

You can remedy this by reinstalling SteamOS from a USB flash drive, which will most likely keep your games and other content (screenshots, and other files stored on the primary SSD) stored on your Deck intact, but it also carries the possibility of deleting all your data – proceed with caution and triple-check what you type in, be especially aware of the spaces and type the exact name of your external SSD.

First of all, open Konsole, type the following command and then type the sudo password when prompted:

sudo nano /etc/fstab

Enable Automatic SSD Mounting 1

This will open the Linux mount table where you can add new drives for the system to automount at boot. You should see something similar to the screenshot below, just without the bottom line, the one that starts with “UUID.”

Enable Automatic SSD Mounting 2

Once you open the mount table, open KDE Partition Manager, right-click the external SSD partition (not the SSD itself, but the partition, as shown below), and then click the Properties tab.

Enable Automatic SSD Mounting 3

Once you open Properties, look for the UUID line, select and copy the entire string of letters and numbers, like shown below. DO NOT select the “Partition UUID” line!

Enable Automatic SSD Mounting 4

After you copy the UUID of your external SSD, go to Konsole, where you should have the mount table opened. Scroll down to the end of it with your mouse or use the arrow keys on the keyboard and type the following:

UUID=Your External SSD UUID /run/media/deck/your SSD label ext4 defaults,nofail 0 0

In our case, the full command looks like this:

UUID=95869bae-2818-40b2-ac78-a1e5e20f278f /run/media/deck/ExtSSD ext4 defaults,nofail 0 0

Once you enter the entire command, press CTRL+S to save it. When you see the notification “Wrote 11 lines” like below, you should be good to go. Press CTRL+X to close the mount table and then exit Konsole.

Again, triple-check to see if everything looks right; If you mess something up, your Deck will enter infinite boot after rebooting it without the external SSD attached to it.

Enable Automatic SSD Mounting 2

And that should be it, you now enabled automatic external SSD mounting for your Steam Deck.