cold plug support

["Dieter Stüken" <stueken@conterra.de>]

I followed the recent discussion about ACPI and hotplug and understand
some of the complications with ACPI if the event is triggered by the
device itself, if it is disrupted unexpectedly.

What I need, however, would be the possibility, just to replace a disks
without reboot. I will umount it first and then suspend/shutdown it somehow,
so it should disappear from /sys/block. Thus I can safely unplug it and attach
a new disk. If my hardware is unable to recognize the new disk instantaneously
this is not a problem. I may easily activate some scanning process to find
and activate the new disk. To accomplish this, IMHO there is no need to solve
all the hotplug problems first.

This would be a BIG enhancement for me (and may be others) to keep my disk
servers up and running. May be some of these steps are already implemented,
but then I'm missing some HOWTO. Else I like to hear if his kind of cold-plug
is aimed some day, or if nobody really needs this besides be :-)

Dieter.
-- 
Dieter Stüken, con terra GmbH, Münster
     stueken@conterra.de
     http://www.conterra.de/
     (0)251-7474-501