sdcard health monitoring

[jpduyx]

There is a github project sdmon that can read the status / remaining endurance of certain sdcards. To make home assistant more robust it would be great to integrate sdmon into haos and enable it somehow for sdcards that can be read with sdmon. And warn a user when it is time to replace the sdcard before it fails.

I tried using the sdmon app https://github.com/MaximizeRr/homeassistant-addon-sdmon

But unfortunately it doesn't seem to work.

Then I thought why is this not integrated into haos for all the platforms that (can) run from sdcard?

The not working addon doesn't seem to have any Mount point so it probably cannot access the sdcard device. But i haven't tried to troubleshoot that further.

I managed to copy the sdmon executable from the container into the host using the ssh 22222 debug terminal.

The size is: 266.5K, would that be okay to monitor the health of perhaps the most vulnerable part of a home assistant device?

Running it from the host with a WD Purple (endurance) sdcard, it can read the status of the card and outputs the following information:

# /tmp/sdmon /dev/mmcblk0
{
"version": "v0.9.0",
"date": "2026-06-24T12:27:25.000",
"device":"/dev/mmcblk0",
"addTime": "false",
"signature":"0x44 0x57",
"SanDisk":"true",
"manufactureYYMMDD": "250704",
"healthStatusPercentUsed": 1,
"featureRevision": "0x1f",
"generationIdentifier": 7,
"productString": "Western Digital                 ",
"powerOnTimes": 196821,
"success":true
}

"healthStatusPercentUsed": 1

So in theory still 99% of the endurance lifetime available.

Unfortunately there is not a single documented industrial standard and it is trial and error to find out which cards work. And I think the output of different cards might also vary. (Perhaps the open home foundation knows their ways into the industry or something to press for an open standard?).

I believe integrating sdmon could help to make home assistant much more robust when running from a supported sdcard on embedded devices.