Quoting Caffeinate The World (mochaexpress@yahoo.com):
> For SCSI we have scsictl to rescan the bus. What about IDE? I see these
> hotswappable IDE kits. How do they work? Does NetBSD support it?

Look, you seem to be obsessing on the importance of RAID
and removable disks.  I've used this forever for ANY OS.
My MAC can deal with it.

I use something called: HARDWARE RAID.

My machine sees a SCSI drive with 500GB (or 5GB when I started with
HW Raid units).

Disk dies and I get notified over serial, an audible alarm
goes off, wahtever.  A spare is brought in if appropriate
(not for stripes, but yes for RAID 3/5).  I can pull the bad
disk or power supply or cable and put a new one in.

If it saves me 5 days of fighting software raid per year,
it costs $0 over 3 years.

Yes, software raid is cheaper to acquire.  But it's slower
and costs far more in maintainance.

Oh, lose the boot disk or CPU and you can't just run the disk case
to another machine and have the data available - in seconds - unless
you are the unusual one to make sure that you have the configs
located elsewhere for immediate use in a panic.

Bring a RAID set down for 4 hours in a busy office and you've
cost yourself FAR FAR more than HW raid costs.