tito <farmatito@???> writes:
> On Fri, 27 Feb 2026 20:52:51 +0000
> Rainer Weikusat via Dng <dng@???> wrote:
>
>> Copy of a message I also sent to 766@???
>> ------------------------
>>
>> 1| mdadm: DeviceDisappeared event detected on md device /dev/md/md3
>> 1| mdadm: DeviceDisappeared event detected on md device /dev/md/md2
>> 1| mdadm: DeviceDisappeared event detected on md device /dev/md/md1
>> 1| mdadm: DeviceDisappeared event detected on md device /dev/md/md0
>> 2| mdadm: NewArray event detected on md device /dev/md0
>> 2| mdadm: NewArray event detected on md device /dev/md1
>> 2| mdadm: NewArray event detected on md device /dev/md3
>> 2| mdadm: NewArray event detected on md device /dev/md2
>>
>> Short version: Won't happen anymore with 4.5, bug can be closed.
>>
>> Long Explanation:
>> -----------------

[...]

>> The underlying issue must have been that a mdadm configuration file
>> either contained the /dev/md/mdN¹ names or just the mdN names without a
>> path.
>
> Hi,
>
> in my case /etc/mdadm.conf contained /dev/md0 as name
> because mdadm 4.4-11devuan3 itself created it that way

If the output quoted above was produced, this cannot have been the
case because the code doesn't do that. It either qualifies an array name
which doesn't start with a / by prepending /dev/md/ or it uses the name
as-is.

> (or maybe I created this array with that dev name,
> could this be the cause? should I have used /dev/md/0?).
> There must have been some other weird interaction with eudev
> or some other corner case I was not able to detect.
> Hope this is fixed in 4.5 as you said.

THe change from 4.4 to 4.5 for this is just that names in the mdadm
configuration which already didn't exist before the Monitor main loop is
entered won't be reported as having disappeared anymore.

> I still wonder why we have started to play this games
> with device names that worked for decades.
> What is the difference in having /dev/md0
> or /dev/md/0 in /dev? What is the advantage
> of this name change?

There is no such name change. Valid md device names can be (N being a
number)

/dev/mdN
/dev/md_dN
/dev/md/<anything>

With <anything> being any 'POSIX portable filename' composed out of
letters, digits, '_', '-' or '.' and not starting with '-'.