2. Using SSD as Expanded Storage (SD Card + SSD)

This chapter will guide you on how to configure an M.2 NVMe SSD as expanded storage for your Raspberry Pi 5 (meaning the system still runs on the SD card, and the SSD is used for storing data).

First, log in to your Raspberry Pi 5 system via SSH or by directly connecting a keyboard and monitor.

Step 1: Modify Boot Configuration

Edit the /boot/firmware/config.txt file. Using the nano editor is recommended:
```
sudo nano /boot/firmware/config.txt
```
Add the following two lines at the end of the file:
```
dtparam=pciex1
dtparam=pciex1_gen=3
```
Press Ctrl+X, then Y, and finally Enter to save and exit the editor.

Step 2: Install Hardware

Power off the Raspberry Pi 5.
Following the instructions for your M.2 adapter, correctly install your NVMe SSD onto the M.2 adapter.

Step 3: Check SSD Recognition

Reconnect the power and boot up the Raspberry Pi 5.
Open a terminal and execute the following commands to check the PCI-E devices and block device list, confirming if your SSD is recognized by the system:
```
lspci
lsblk
```
You should see information similar to NVMe SSD or the specific model name, along with a new block device (e.g., /dev/nvme0n1).

Step 4: Format the SSD

Use the mkfs.ext4 command to format the SSD with the ext4 filesystem. Please replace ``/dev/nvme0n1`` with the actual device name you identified in the previous step.

Warning

Formatting will erase all data on the SSD. Proceed with caution!
```
sudo mkfs.ext4 /dev/nvme0n1
```
The system might prompt you about detecting a partition table; type y and press Enter to continue.
After formatting is complete, use lsblk again to confirm the device status.
```
lsblk
```
Now, /dev/nvme0n1 should no longer have an associated mount point.

Step 5: Mount the SSD

Create a directory to serve as the mount point for the SSD. For example, create a directory named SSD in the user’s home directory:
```
mkdir ~/SSD
```
Manually mount the SSD to this directory:
```
sudo mount /dev/nvme0n1 ~/SSD
```

To make the system automatically mount the SSD on every boot, you need to edit the /etc/fstab file:
```
sudo nano /etc/fstab
```
Add the following line at the end of the file. Again, be sure to replace the device name and mount path with your actual names:
```
/dev/nvme0n1 /home/pi/SSD ext4 defaults 0 0
```
This assumes your username is pi and the mount point is /home/pi/SSD. Modify according to your actual setup.
Press Ctrl+X, Y, Enter to save and exit.
Execute the following command to apply the mount, or simply reboot the Raspberry Pi:
```
sudo mount -a
```
After rebooting, you can use the df -h command to check if the SSD is successfully mounted:
```
df -h
```
You should see /dev/nvme0n1 mounted at /home/pi/SSD.

Step 6: (Optional) Test Read/Write Speed

To get more accurate test results, you can first clear the filesystem cache:
```
sudo sh -c "sync && echo 3 > /proc/sys/vm/drop_caches"
```

Test write speed (writes an approximately 2GB file):

sudo dd if=/dev/zero of=~/SSD/test_write bs=1M count=2000 status=progress

Test read speed (reads the file just written):

sudo dd if=~/SSD/test_write of=/dev/null bs=1M status=progress

After testing, delete the test file:
```
rm ~/SSD/test_write
```

Note

Read/write speeds are affected by various factors like the SSD model, Raspberry Pi load, etc. The test results are for reference only.

At this point, you have successfully configured the M.2 NVMe SSD as expanded storage for your Raspberry Pi 5.