Matthias Drochner writes:
> 
> Is it intended that a spare disk in a raid5 array is not
> autoconfigured?

Yes.

> If yes, why not?

Cause some day it'd be nice if there could be a 'pool of spares' not assigned 
to any particular RAID set.  The idea is that in the event of a component 
failure, a RAID daemon would select a spare from the pool, hot-add it to the
array, and then rebuild.

Part of the problem is that there is no way to 'delete' a hot spare from a 
set, so if you added it to one array, and then discovered you really needed it 
on another, there is no (easy) way to move it over.  Someday we'll be able to 
remove hot spares too :) 

> And what is the canonical way to add it later? A "manual"
> "raidctl -a" invocation -- no rc.d support?

"raidctl -a" works fine.  You could do something like that in rc.local if you 
wanted.

Later...

Greg Oster