BUILD NOTES:

Burn the emon image to an SDHC

Do an initial set up of emoncms and expand to fill the SDHC
Go to the web interface and set up an account then create a log to feed (for test purposes)

Poweroff and remove the SDHC and transfer to a PC

Create a txt file cmdline.txt.sda with the following content by adapting the existing cmdline.txt:

dwc_otg.lpm_enable=0 console=tty1 elevator=noop root=/dev/sda1 rootdelay=5 rootfstype=ext4 fsck.repair=yes rootwait

Also:
Make a copy of cmdline.txt and rename to cmdline.txt.original (a precation)

Prepare the USB HDD eg: using Paragon Hard Disk Manager to create an NTFS partition

Re-insert SDHC and connect USB HDD and power on RPi

Now first modify /etc/fstab because it will be copied to the USB HDD in the later steps

But before doing so, copy the original fstab into the first (/boot) partition of the SDHC (a precaution)

This is the original /etc/fstab:

tmpfs           /tmp            tmpfs   nodev,nosuid,size=30M,mode=1777 0  0
tmpfs           /var/log        tmpfs   nodev,nosuid,size=50M,mode=1777 0  0
tmpfs           /var/lib/dhcp   tmpfs   nodev,nosuid,size=1M,mode=1777 0  0
tmpfs           /var/lib/dhcpcd5 tmpfs nodev,nosuid,size=1M,mode=1777 0  0
tmpfs           /var/lib/openhab tmpfs  nodev,nosuid,size=40M,mode=1777 0  0
proc            /proc           proc    defaults 0 0
/dev/mmcblk0p1  /boot           vfat    defaults,noatime,nodiratime 0 2
/dev/mmcblk0p2  /               ext4    defaults,ro,noatime,nodiratime,errors=remount-ro 0 1
/dev/mmcblk0p3  /home/pi/data   ext2    defaults,rw,noatime,nodiratime,errors=remount-ro 0 2

Comment out the last 2 lines and add these 2 lines using sudo nano /etc/fstab

/dev/sda1  /               ext4    defaults,ro,noatime,nodiratime,errors=remount-ro 0 1
/dev/sda2  /home   ext2    defaults,rw,noatime,nodiratime,errors=remount-ro 0 2

Now create 2 partitions on the USB HDD and copy to these as follows ...

sudo apt-get install rsync parted
sudo parted --script "/dev/sda" mklabel gpt
sudo parted --script --align optimal "/dev/sda" mkpart primary ext4 0% 10%
sudo parted --script --align optimal "/dev/sda" mkpart primary ext2 10% 100%

(10% is selected because it creates an sda1 of approx 12 Gb on a 120 Gb HDD - adjust as appropriate)

sudo mkfs -t ext4 -L rootfs /dev/sda1
sudo mkfs -t ext2 /dev/sda2

Check things are OK to this point with:
sudo parted --script "/dev/sda" print

If OK, continue with:
sudo mount /dev/sda1 /mnt
sudo rsync -ax / /mnt
sudo mount /dev/sda2 /mnt
sudo rsync -ax /home/pi /mnt
sudo rsync -ax /home/pi/data /mnt/pi

Finally do sudo cp /boot/cmdline.txt.hdd_sda /boot/cmdline.txt
Then reboot

Browse to the web interface, log in & go to Setup > EmonHub > Restart
Then > View log to check all is OK

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