avoidik/README.md

## README.md

      
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    Raspberry Pi from SD to USB

How to switch over from SD-card to USB-attached device (USB thumbstick, USB enclosed SSD or HDD, etc.) to have more durable storage option.
Steps


Connect USB device to your RPI


Make sure USB device visible by the system
sudo fdisk -l
sudo lsblk
Usually mmcblk0 is your SD-card, and sda, sdb, sdX are attached USB devices, in my case it was sda.
Make sure there is no sensitive data stored on the target USB device.
If it's new USB device there should be no partitions reported by fdisk for it.
You may want to clean target device using sudo sfdisk --delete /dev/sda (be very careful, it will delete everything on your target device)


Install rpi-clone
git clone https://github.com/billw2/rpi-clone.git 
cd rpi-clone
sudo cp rpi-clone rpi-clone-setup /usr/local/sbin
sudo rpi-clone-setup -t $(hostname -s)
sudo rpi-clone -s


Clone SD-card to USB device
sudo rpi-clone sda # replace sda here with your device name
This may take some time depending on how much data you have, storage performance, running applications, clients connected, etc.
During the process few questions will be asked, read carefully and answer.
On the last step where it's asked to examine mounted clone run another connection to RPI, keep existing intact.
If you've accidentally skipped it just remount it manually:

sudo mount /dev/sda6 /mnt/clone/boot.
sudo mount /dev/sda7 /mnt/clone


Identify partitions
Target device will have the same partitions layout as in source device. We need to find out boot and last partition ids.
sudo lsblk -o name,mountpoint,size,partuuid /dev/sda6 # clone of mmcblk0p6 mounted as /boot
sudo lsblk -o name,mountpoint,size,partuuid /dev/sda7 # clone of mmcblk0p7 mounted as / or root
Write down PARTUUID column, in my case these were 3b4344a4-06 for boot and 3b4344a4-07 for root partition respectively


Change cmdline.txt
To be able to boot from the target device we have to change cmdline.txt file:

change root=/dev/mmcblk0p7 to root=PARTUUID=3b4344a4-07 which is the root partition id
append at the end of the line rootdelay=5 option to wait while attached device is initialized at boot time

Complete example:
console=serial0,115200 console=tty1 root=PARTUUID=3b4344a4-07 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait rootdelay=5

If you'll try to boot without this change you'll get endless Waiting for root message.
Note: there is one interesting caveat, if you'd like to use LABEL or UUID instead of PARTUUID you must create initramfs/initrd file, hence additional step will be required. Do not use PARTUUID with initrd.
If you're going to use PARTUUID then you don't need this step (I repeat, skip it and follow the next step).

make sure root= set to something like root=LABEL=USB-ROOT
cd /mnt/clone/boot/
generate initrd file with mkinitramfs -o initrd.sda
append initramfs initrd.sda followkernel after rootdelay=5

Complete example:
console=serial0,115200 console=tty1 root=LABEL=USB-ROOT rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait rootdelay=5 initramfs initrd.sda followkernel


Change fstab
After the boot process has been completed we would need to mount correct partitions.
Open /mnt/clone/etc/fstab and do the following:

change device /dev/mmcblk0p6 to PARTUUID=3b4344a4-06 (remember to use your own id)
change device /dev/mmcblk0p7 to PARTUUID=3b4344a4-07 (remember to use your own id)

Complete example:
proc            /proc           proc    defaults          0       0
PARTUUID=3b4344a4-06  /boot           vfat    defaults          0       2
PARTUUID=3b4344a4-07  /               ext4    defaults,noatime  0       1


Unmount
Now return back to the initial terminal where we've left rpi-clone process open and hit enter to unmount all partitions.
Make sure you don't have the second terminal open somewhere at the mounted paths.


Test
Shutdown RPI with sudo shutdown -h now, disconnect PSU, unplug SD card, plug PSU in, verify