Behind the scenes of the "move data disk" feature

[FloatingBoater (James Derrick)]

Hi,
These threads might be of use:

Home Assistant Yellow installation

I installed my Home Assistant Yellow today with a Raspberry PI CM4 with 32 GB eMMC and a 128 GB M.2 SSD. The Home Assistant installer used the eMMC storage for installation and data but I wanted the M.2 SSD to be used. The Home Assistant hardware overview does not show the M.2 SSD at all Is there a way to verify if the M.2 is initialised and formatted? Furthermore could I move the Home Assistant OS and data to de M.2 SSD?

Home Assistant Yellow installation

Not a problem - I too wanted a PoE device, but the supply issues around CM & RPi increased the risk so went with a kit. The RPi foundation have a sensible policy of releasing some stock to hobbyists, but keeping business users solvent with priority access to a constant trickle of devices. I suspect this is also why the Pico 2040 was created - easier to get made, and might reduce demand for full RPi4. FYI - after a “move datadisk”, it looks like all user data for the HASS container is indeed no…

From my greybeard sysadmin understanding:

• What data exactly will remain on the SD card
  Unless you start a fresh HAOS install to a specific disc (which seems to be your existing config…), only the user data partitions will be copied onto the new “data disk”. All HAOS, HASS, and code will remain as before.
  For a worked example see this post with partition data.
• Can this be undone
  At the basic level, disconnect the “data disk” and reboot - the old data is still there, so without the newer version, it reverts.
  Remember HAOS is an appliance, so to undo properly, backup, wipe, reinstall, restore.
• What happens once I would restore a full backup
  HAOS seems to work at arms length from HASS - HAOS sets up which physical partitions are mounted, and HASS restore restores multiple tar archives to the file system, regardless of the actual mount points.

Have I tested this with references to the HASS admin scripts in GitHub? Nope!

Basically, these are educated guesses from what mount looks like from HASS userland without developer shell access to the host HAOS.

I’d create a test rig, and do the things you are interested in to confirm what you need to know. A RPI3b+, two uSD, and one USB reader would be enough for this.

If this helps, this post!