How to replace CM4 module in Home Assistant Yellow

aschmere · November 21, 2023, 9:12pm

I am currently running a pretty standard Home Assistant Yellow hardware setup (PoE Kit with CM4 2GB RAM Storage Lite board/no Wifi) with a 250GB Samsung M2 SSD. Basically happy so far, but RAM is sometimes at almost 80% and hence would like to replace the current CM4 board with a CM4 board with 8GB RAM, using the same specs otherwise, i.e. Storage Lite 0GB/no Wifi.
Questions:

Is the workflow to be executed as simple as a) powering down the HA Yellow, b) replace the CM4 module as documented under Removing the Raspberry Pi Compute Module 4 (CM4) – Home Assistant Yellow and Installing the Raspberry Pi Compute Module 4 (CM4) – Home Assistant Yellow c) Powering up the Yellow again, booting the already existing installation on the Samsung M2 SSD?
Or do I need to apply some other hacks like setting the boot order properly on the new board?

aschmere · November 25, 2023, 1:44pm

Meanwhile I could answer this question myself. These are the steps I executed along with the results:

I took a backup of my HA config and shut down my Yellow.
I replaced the before-mentioned 2GB Lite Raspberry Pi CM4 module with an 8GB Lite module.
I just powered on the Yellow again and it recognized the new module with 8GB RAM and also booted properly from the existing installation on the M2 drive.
Only issue I had, which, however, may be completely unrelated to the CM4 module replacement: The OpenThread border router in HA did not recognize my thermostats anymore. The log files of the OpenThread BT also showed some mDNS issues. Resolution was to just restart the OpenThread BT add-on.

wireless1710 · December 30, 2023, 12:24am

Newbie. So I got my Yellow today. And I THOUGHT I ordered with the 4 GB compute 4. Apparently what I got was a Yellow with 2 GB and a SECOND compute 4. I’d wager that one has 4 GB on it. So my question is, do a backup, shutdown, remove the heat sink, put the second compute 4 on the mother card, move the heat sink over (can you do that?), then power it up. I’d wager no HA OS on that one so I assume follow whatever script I can find to do that as well. Thanks.

BorisTS · March 19, 2024, 12:44pm

Hello. This solution run only with a Lite version ? I ordred a CM4 with eMMC BUT all is on my M2 drive. If I swap my CM4 will it boot ? if not, any recomendation ? Thanks for help.