mdadm.conf hotplug POLICY

[bug556610 at arcor.de]

Hello,

mdadm claims to support hotplugging raid member devices for 
some time now, and it may only be a configuration issue to make
it work in debian out of the box.
https://raid.wiki.kernel.org/index.php/Hotplug

Unfortunately, from the mdadm.conf man page I could not understand how to configure
proper hotplug POLICY lines, that simply allow what one would expect as default:

Always re-add (re-sync) a previously removed/failed disk or partition to its matching array,
no matter the port used to connect the disk.

I can understand that things like adding new (unknown) disks to arrays should not
be the default (and this ok to require some configuration). Nevertheless, I think any
modern operating system should automatically re-add a priorly removed disk when it is plugged-in
again.

Hopefully someone can chim in with some good mdadm.conf hotplug POLICY lines to be added for the
default debian configuration?

Kind Regards,
Christ