Libre “Le Potato” SSD Boot Guide

The “Le Potato” by Libre Computers is a $40 single board computer. That is incredibly cheap in 2022 as anyone who has tried to buy a Raspberry Pi recently can tell you. There aren’t a lot of guides out there for how to best utilize it though so today I’d like to publish a guide for it for one of the best upgrades you can do with any SBC: upgrade to SSD storage!

This method requires a sacrificial SD card to serve as the bootloader. After booting though it will use your SSD for the system’s root filesystem. We will then benchmark it to measure the improvement/gains.

Let’s begin!

Hardware Used

Preparing SD Card

First you should have a completely working installation on a SD card of the OS that you would like to use. I used Armbian for this guide (recommended) so if your partitions are different it may be your flavor of Linux and need slightly altered instructions.

If you have an already working installation you want to move to your SSD you can use this as well most likely.

You should completely update first with:

sudo apt update && sudo apt full-upgrade

If you are using a different package manager then update the image however you need to for your distribution.

Preparing SSD

Now we are going to connect your SSD to the “Le Potato”. First we are going to completely remove all partitions from the drive so it’s completely blank. If you only have one drive plugged into the “Le Potato” (and nothing else) this should be /dev/sda.

sudo fdisk /dev/sda

Now remove all partitions from the device. If you press “p” it will print out the partitions. Here’s an example on mine:

james@lepotato:~ $ sudo fdisk /dev/sda

Welcome to fdisk (util-linux 2.36.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.


Command (m for help): p
Disk /dev/sda: 232.89 GiB, 250059350016 bytes, 488397168 sectors
Disk model: CT250MX200SSD1  
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: 0x3cedfd53

Device     Boot  Start      End  Sectors  Size Id Type
/dev/sda1         2048   264191   262144  128M  c W95 FAT32 (LBA)
/dev/sda2       264192 62550016 62285825 29.7G 83 Linux

Command (m for help): d  
Partition number (1,2, default 2): 1

Partition 1 has been deleted.

Command (m for help): d
Selected partition 2
Partition 2 has been deleted.

Command (m for help): w
The partition table has been altered.
Failed to remove partition 1 from system: Device or resource busy
Failed to remove partition 2 from system: Device or resource busy

The kernel still uses the old partitions. The new table will be used at the next reboot. 
Syncing disks.

Even though I got the device was busy error after unplugging and replugging the SSD the partition table was clear.

Once the drive is all cleared off you’re ready for the next step.

Cloning Installation to SSD

We’re now ready to clone your installation to the SSD. If you don’t have the eMMC attached your current root filesystem should be /dev/mmcblk0p1 (or /dev/mmcblk1p1 on some operating systems, check ls /dev or blkid).

We can now copy your drive to the SSD with the following command:

cat /dev/mmcblk0 > /dev/sda

Wait for the operation to complete (there won’t be any output but you will have a cursor again and be able to type new commands). It may take several minutes or longer. You are copying an entire drive from one to another basically with that one command.

Mine took almost 40 minutes (although I was using a 64GB SD card and the larger SD card you use the longer it will take to copy the whole drive).

If you are having any trouble with permissions try becoming “root” first with:

sudo su

Now try running the command again and as the superuser you should not encounter any permission errors.

Change SD card’s UUID

Now unplug the SSD and plug it back in. We need to change our SD card’s UUID so that it doesn’t try to boot from that partition. We can set it to a random one with the following command:

sudo tune2fs -U random /dev/mmcblk0p1

We can verify that it has changed with blkid like this:

james@lepotato:~$ sudo blkid
/dev/mmcblk0p1: LABEL="armbian_root" UUID="8bd51dc9-54c1-4f39-a149-459c638c9521" BLOCK_SIZE="4096" TYPE="ext4" PARTUUID="39524a4b-01"
/dev/sda1: LABEL="armbian_root" UUID="8ed60109-91ba-4708-b67f-1ae2da76894c" BLOCK_SIZE="4096" TYPE="ext4" PARTUUID="39524a4b-01"
/dev/zram0: UUID="40c660fe-280b-47d4-8d05-927fc39358b8" TYPE="swap"
/dev/zram1: LABEL="log2ram" UUID="25cbe7ff-d7da-4151-8344-f2167bbd4f8c" BLOCK_SIZE="4096" TYPE="ext4"

Notice that /dev/sda1 and /dev/mmcblk0p1 no longer have matching UUIDs. This is exactly what we want.

Run fsck

Before we reboot run e2fsck on the drive like this:

sudo e2fsck -yf /dev/sda1

This will prevent you from having to run fsck on the CLI the first time you try to boot.

Reboot and Verify

Now reboot the “Le Potato” with:

sudo reboot

With any luck you should be booted using your SSD! We can verify this with the mount command like this:

james@lepotato:~$ mount
/dev/sda1 on / type ext4 (rw,noatime,errors=remount-ro,commit=600)
/dev/sda1 on /var/log.hdd type ext4 (rw,noatime,errors=remount-ro,commit=600)
/dev/zram1 on /var/log type ext4 (rw,relatime,discard)

Here we can see that our root partition (/) is indeed on /dev/sda1 and not /dev/mmcblk0p1. Success!

Testing Performance

You can verify the performance of your SSD on Pi Benchmarks using the following command:

sudo curl https://raw.githubusercontent.com/TheRemote/PiBenchmarks/master/Storage.sh | sudo bash

SD Card Test

To show the improvement between having a SD card rootfs and having a SSD rootfs I did a before test here with the SD card:

     Category                  Test                      Result     
HDParm                    Disk Read                 21.54 MB/s               
HDParm                    Cached Disk Read          21.83 MB/s               
DD                        Disk Write                16.3 MB/s                
FIO                       4k random read            1804 IOPS (7219 KB/s)    
FIO                       4k random write           925 IOPS (3700 KB/s)     
IOZone                    4k read                   6720 KB/s                
IOZone                    4k write                  2031 KB/s                
IOZone                    4k random read            5617 KB/s                
IOZone                    4k random write           2956 KB/s                

                          Score: 939                                                  

SSD Test

     Category                  Test                      Result     
HDParm                    Disk Read                 33.95 MB/s               
HDParm                    Cached Disk Read          33.44 MB/s               
DD                        Disk Write                33.6 MB/s                
FIO                       4k random read            6462 IOPS (25850 KB/s)   
FIO                       4k random write           6148 IOPS (24593 KB/s)   
IOZone                    4k read                   12903 KB/s               
IOZone                    4k write                  13287 KB/s               
IOZone                    4k random read            11344 KB/s               
IOZone                    4k random write           15181 KB/s               

                          Score: 3,451                                        

You may view the full benchmark on Pi Benchmarks for this guide here.

Wow, that’s quite a dramatic improvement. We went from 939 to 3,451. That’s about a 3.5x performance increase! You can also look at the raw IOPS and MB/s numbers on HDParm and the various test categories if you are more familiar with those to see the improvement.

Conclusion

Even though we are limited to USB 2.0 bus speeds we can still achieve about 3.5x the performance of the SD card using a SSD with a USB to 2.5″ SATA adapter. This is definitely worthwhile as it was on boards like the Raspberry Pi 3 that had USB 2.0 as well.

I haven’t tested the eMMC modules for the “Le Potato” yet because they are currently out of stock on Amazon. Because of the USB 2.0 bus there’s a chance that eMMC modules might perform faster than an SSD.

The SSD performance is substantially higher than SD cards though for sure as we’ve determined through our benchmarking!

Other Resources

If you are moving from a Raspberry Pi to a “Le Potato” see my Raspbian Portability Tool for Libre Boards Guide

Don’t miss my review of the Libre Computers “Renegade” board which is $10 more than the “Le Potato” and gives you a USB 3.0 port

You may be interested to see my Libre Computers “Le Potato” Review

Make sure to check out my ODROID XU4Q review which includes eMMC tests and benchmarking

For an awesome retro gaming handheld console check out the ODROID Go Super