> But you really should NOT [hot-swap devices and rescan the bus],
> unless you really have a hot-swappable scsi bus and disk.  Besides
> risking to damage the hardware, the machine might panic if it tries
> to handle a page fault while you're connecting or disconnect the bus.

What sort of hardware damage is at risk, assuming of course that the
bus is idle when the connection is being made/broken?

I do this - hot-connect and -disconnect scsi devices - routinely,
ensuring that the bus is idle by nerve-pinching the machine into ddb
for the duration of the operation (L1-A on a Sun, Ctl-Alt-ESC on an
Intel, BREAK on a serial-console machine).  Except for once when the
kernel apparently had a transfer in progress when I nerve-pinched it
and the machine crashed when I told it to continue, I've never had any
trouble of any sort.

Of course, this has been on relatively tolerant hardware - old non-fast
non-wide non-differential stuff....

					der Mouse

			       mouse@rodents.montreal.qc.ca
		     7D C8 61 52 5D E7 2D 39  4E F1 31 3E E8 B3 27 4B