On Wed, 04 Jun 2025 12:26:19 +0100
Rainer Weikusat via Dng <dng@???> wrote:

> Rainer Weikusat via Dng <dng@???> writes:
> > Not very amusing story someone might nevertheless find quite funny:
> >
> > I used to run RAID1 system with two RAID devices, one for 'system' and
> > one for 'data', with half of the array residing on an internal NVME
> > device and the other on an USB disk. I recently bought a webcam. When I
> > initially plugged that into an USB port, nothing happened. I then tried
> > a reboot. This caused the camera to appear (no idea if it also works)
> > but additionally, convinced something in the initramfs to remove all the
> > partitions on the USB disk from the corresponding RAID devices, thus
> > leaving me with two degraded arrays.
> >
> > I'll now try to figure out how I can get my missing partitions back ...
>
> Simply re-adding the lost partitions to the RAIDs they belonged to via
>
> mdadm --manage /dev/mdX --add /dev/sdaX
>
> turned out ot work. I now again have to fully functioning RAID devices
> which get autostarted on boot. Nevertheless, this was an 'unexpected
> feature' I could easily have done without.

Hi,
probably the disk was not fast enough to spin up for mdadm
due to the added cam and/or underpowered during the spin up.
Solution could be to power it separately with a PSU otherwise
this will randomly happen again at boot (typical of NAS with many disks
and underpowered or dying PSU showing disks kicked out at boot).
Other solution is to skip USB altogether and use a SATA or ESATA port
or card and power it directly with the PC's psu (some wiring needed,
or adapters or sata power splitters).

Hope this helps,
ciao,
Tito