Ok done a bit more digging and the booting from SSD vs SD card turned out to be a simple edit of the fstab in the SSD /etc directory. here are the changes I made. (I’m not sure if there is a way to format this).
*#/dev/mmcblk0p1 /boot vfat defaults 0 2*
*#/dev/mmcblk0p2 / ext4 defaults,noatime,nodiratime 0 1*
*#/dev/mmcblk0p3 /var/opt/emoncms ext2 defaults,noatime,nodiratime 0 2*
*/dev/sda1 /boot vfat defaults 0 2*
*/dev/sda2 / ext4 defaults,noatime,nodiratime 0 1*
*/dev/sda3 /var/opt/emoncms ext2 defaults,noatime,nodiratime 0 2*
My method was as follows:
- Image a new SDcard with the latest emoncms image from the site using ethcher.
- Boot the new SDcard create a login and do a full update on the admin page and reboot.
- Check that emoncms is running as you expect then shutdown.
- Connect your preferred SSD, mine is a Geekworm X857 card with a 128GB mSata card which attaches to one of the USB3.0 ports.
- Boot the pi from the latest raspian desktop version.
- Insert the emoncms SDcard you prepared earlier in the a USB card reader and attach to the pi.
- Using SD Copy utility to copy the emoncms SDcard to the SSD, being careful your system now has 3 disks attached. my SSD was /dev/sda and the emon SD card was /dev/sdb. So I copied sdb to sda. SD Copy does a bitwise copy probably using ‘dd’.
- Once finished shutdown the pi and remove the usb card reader with your emon SD card, then reboot.
- You should find that once booted the SSD filesystems should have mounted and be visible on your desktop. One will be /boot, two will be /root and the third the emoncms (ext2) partition.
- I then looked for /etc/fstab in the /root filesystem, make the edits above, then shutdown.
Now remove the SD card and reboot, if if you have the latest boot code the boot sequence looks for an SD card if one isn’t present it goes on to try to boot from a USB device.
Mine booted normally. My pi is a 4B, 4GB. I hope this help anyone trying to boot from an SSD. If there are questions I’ll try to help if I can.
Next is to move my working system data to this new setup