[mdlug] "Device busy" errors and RAID setup issues

[David McMillan]

	Not sure what I have going on here.  I've built myself a (intended) 
RAID server with five SATA 1TB drives dedicated to the RAID array 
(separate dedicated boot drive), running Jaunty Jackalope (I tried a few 
server-dedicated distros, but JJ is what I'm comfortable with).  The 
HOWTOs I've found on the net make building a RAID array using mdadm 
pretty simple, but I keep getting "Device or resource busy" on one or 
more of the RAID drives when I try to do an mdadm build.  What's really 
odd is that the "busy" drive(s) are different each time I reboot the 
machine.  These drives have been fdisk'd to auto-detect RAID partitions, 
are completely empty, and are not mounted -- never *have been* mounted, 
for that matter.  Running an lsof turns up nothing using any of the 
/dev/sd* drives aside from the boot drive.  'tis a pozzlement.

	The other problem is that when I experimentally tried creating a RAID 
array out of the drives that *weren't* busy, some odd things happened. 
The array built successfully, as far as I could tell -- no error 
messages, and it showed up as an active /dev/md0 in /proc/mdstat, but 
when I rebooted the computer, mdadm won't show /dev/md0 as an active 
array device, although it'll accept start/stop commands.  Trying to 
build the array again from scratch yields a bunch of "device appears to 
already be part of a RAID array" error messages.  Thing is, I can't seem 
to get rid of the old array so I can start over again.