I've got a regularly scheduled (read: nagios) job that runs 

lsraid -a -A /dev/mdN  {N 0-4}

and sporadically through out the day, it decides that there is NO,
repeat NO output to that lsraid command.  When I run it by hand, it's
always clam happy and tells me the md is online with the appropriate
number of devices.

If the md had actually faulted somehow, I'd have noticed since one of
the md's is housing a database and I'm fairly sure that someone,
somewhere, would have complained about something not being as
expected. 

Any ideas?

David