If the Raspberry Pi is not able to boot from your external drive, you can boot from a microSD card and use the external drive to store all the application data.
Status: Tested v3
Table of contents
- Steps required
- Operating system
- System configuration
- Continue with the guide
To boot from a microSD card and store the data on an external drive, there are a few additional steps compared to the default RaspiBolt guide. Below is a summary of the main differences, with detailed guidance in the following sections.
- Operating system:
- write the operating system to the microSD card instead of the external drive
- System configuration:
- attach the external drive
- test the USB3 performance
- format the drive
- mount the drive to
When writing RasPiOS to the boot medium, use a high-quality microSD card of 8+ GB instead of the external drive.
Connect your external drive to the Raspberry Pi using one of the blue USB3 ports.
In case your external drive shows poor performance, follow the Fix bad USB3 performance instructions, as mentioned in the guide.
We will now format the external drive. As a server installation, the Linux native file system Ext4 is the best choice for the external hard disk.
List all block devices with additional information. The list shows the devices (e.g.
sda) and the partitions they contain (e.g.
$ lsblk -o NAME,MOUNTPOINT,UUID,FSTYPE,SIZE,LABEL,MODEL > NAME MOUNTPOINT UUID FSTYPE SIZE LABEL MODEL > sda 931.5G Ext_SSD > `-sda1 2219-782E vfat 931.5G > mmcblk0 14.8G > |-mmcblk0p1 /boot DBF3-0E3A vfat 256M boot > `-mmcblk0p2 / b73b1dc9-6e12-4e68-9d06-1a1892663226 ext4 14.6G rootfs
If your drive does not contain any partitions, follow this How to Create a Disk Partitions in Linux guide first.
Make a note of the partition name of your external drive (in this case “sda1”).
Format the partition on the external drive with Ext4 (use
[NAME]from above, e.g.
🚨 This will delete all existing data on the external drive!
$ sudo mkfs.ext4 /dev/[NAME]
The external drive is then attached to the file system and becomes available as a regular folder (this is called “mounting”).
List the block devices once more and copy the new partition’s
UUIDinto a text editor on your main machine.
$ lsblk -o NAME,MOUNTPOINT,UUID,FSTYPE,SIZE,LABEL,MODEL > NAME MOUNTPOINT UUID FSTYPE SIZE LABEL MODEL > sda 931.5G Ext_SSD > └─sda1 3aab0952-3ed4-4652-b203-d994c4fdff20 ext4 931.5G > mmcblk0 14.8G > |-mmcblk0p1 /boot DBF3-0E3A vfat 256M boot > `-mmcblk0p2 / b73b1dc9-6e12-4e68-9d06-1a1892663226 ext4 14.6G rootfs
fstabfile and add the following as a new line at the end, replacing
123456with your own
$ sudo nano /etc/fstab
UUID=123456 /data ext4 rw,nosuid,dev,noexec,noatime,nodiratime,auto,nouser,async,nofail 0 2
🔍 more: complete fstab guide
Create the data directory as a mount point. We also make the directory immutable to prevent data from being written on the microSD card if the external drive is not mounted.
$ sudo mkdir /data $ sudo chattr +i /data
Mount all drives and check the file system. Is “/data” listed?
$ sudo mount -a $ df -h /data > Filesystem Size Used Avail Use% Mounted on > /dev/sda1 938G 77M 891G 1% /data
The swap file acts as slower memory and is essential for system stability. MicroSD cards are not very performant and degrade over time under constant read/write activity. Therefore, we move the swap file to the external drive and increase its size as well.
Edit the configuration file, add the
CONF_SWAPFILEline, and comment the entry
CONF_SWAPSIZEout by placing a
#in front of it. Save and exit.
$ sudo nano /etc/dphys-swapfile
CONF_SWAPFILE=/data/swapfile # comment or delete the CONF_SWAPSIZE line. It will then be created dynamically #CONF_SWAPSIZE=100
Recreate and activate new swapfile
$ sudo dphys-swapfile install $ sudo systemctl restart dphys-swapfile.service
That’s it: your Raspberry Pi now boots from the microSD card while the data directory
/data/ is located on the external drive.
You can now continue with the RaspiBolt guide.
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