NVMe

This section introduces how to use the NVMe hard drive function on the Raspberry Pi, laying the foundation for subsequent project development.

Note: The PCIe interface must be enabled before using this function.

Enabling the PCIe Interface

If the PCIe interface is not enabled, enable the PCIe interface first.
Check supported filesystem types by typing sudo mkfs. and pressing Tab to see available filesystem suffixes.
```
sudo mkfs.
```
List all drives
```
lsblk
```
Confirm the target partition
Formatting will erase all data on the target partition. This step applies to an existing target partition; if a partition has not been created yet, complete "Drive Partitioning" first. Confirm that /dev/nvme0n1p1 is the partition to be formatted, and back up your data before proceeding.
To format /dev/nvme0n1p1 as ext4, run the following command:
```
sudo mkfs.ext4 /dev/nvme0n1p1
```

If the PCIe interface is not enabled, enable the PCIe interface first.
List all drives (for more details, run sudo fdisk -l)
```
lsblk
```
To repartition /dev/nvme0n1, execute the following command (note: the device number is the base device, do not add p1, as p1 indicates a partition):
```
sudo fdisk /dev/nvme0n1
```
After adding a partition with n, finally type w to save and exit.
fdisk command functions:
- n Create a new partition
- q Quit without saving
- p Print the partition table
- m Print the menu
- d Delete a partition
- w Write table to disk and exit
- t Change a partition's system ID

If the PCIe interface is not enabled, enable the PCIe interface first.
Confirm the target mount directory. If the toshiba folder does not exist in the current directory, create it:
```
sudo mkdir toshiba
```
List all drives (for more details, run sudo fdisk -l)
```
lsblk
```
To mount /dev/nvme0n1 to the toshiba folder in the current directory, for example:
```
sudo mount /dev/nvme0n1p1 ./toshiba
```
Check the file system disk space usage
```
df -h
```

Note: Auto-mounting is only used when the drive is not the system disk, i.e., when it functions as additional storage. Perform this configuration only in such cases
If the PCIe interface is not enabled, enable the PCIe interface first.
Modify the fstab file
```
sudo nano /etc/fstab
```
Add the following line at the end of the file (/dev/nvme0n1p1 is the device, /home/pi/toshiba is the mount directory, ext4 is the filesystem type, defaults are the default mount options):
```
/dev/nvme0n1p1  /home/pi/toshiba  ext4  defaults  0  0
```
Test the mount configuration with the following command. Reboot only after confirming it works; otherwise, a mount failure may prevent the system from booting.
```
sudo mount -a
```
After confirming the mount is successful, reboot the Raspberry Pi.
```
sudo reboot
```
After reboot, verify the mount status
```
lsblk
```

If the PCIe interface is not enabled, enable the PCIe interface first.
Check the mount status
```
lsblk
```
After confirming the mount is successful, navigate to the mount directory (here /home/pi/toshiba).
```
cd /home/pi/toshiba
```

Copy data from Raspberry Pi memory to the drive (Write Test)

# Clear memory before the write test
sudo sh -c "sync && echo 3 > /proc/sys/vm/drop_caches"
sudo dd if=/dev/zero of=./test_write count=2000 bs=1024k

Write Test Result

Copy data from the drive to Raspberry Pi memory (Read Test)

# Clear memory before the read test
sudo sh -c "sync && echo 3 > /proc/sys/vm/drop_caches"
sudo dd if=./test_write of=/dev/null count=2000 bs=1024k

Read Test Result

Note: Performance varies depending on the drive and the environment on the Raspberry Pi. Some drives may be speed-limited. For accurate performance testing, use a PC.