Adding SCSI devices to a live machine

[chuck <chuck_(_at_)_Yerkes_(_dot_)_com>]

I think I asked this during version 2.2 and there was no answer.
Well, I've spent a number of months off the list (moving, dealing
with moving, new job, etc) and need to re-ask it.

Have a couple SCSI devices that aren't on all the time.  These
include a scanner, a tape and a disk or two that are often just
loud an unnecessary for day-to-day use (contains /usr/{src,obj,ports}
and other sources and the like).

Now when I boot the machine, I turn these on so they get 'discovered.'
Sometimes, however, the machine does a suprise boot.  It's livable,
but I then can't 'see' the devices anymore.

The solution right now it to find some time to do a 'managed' reboot,
but this is less than ideal.  The machine is a desktop/home machine, so
these things will just not be kept on 24/7.  If it helps any analysis,
security level is set to '-1' because the machine does not need/want
the higher security that my net machines do.

Under SunOS/Solaris, I can run the 'format' command and the machine
will scan the bus(es), send the SCSI reset or init (I think), and the
device is available.

I suppose during the device discovery phase of the boot, structures are
allocated for each SCSI device found.  It is possible to add to these
structures during run-time?

I ask because I don't think I'm the only person using a computer that
ever turns a device off or adds a device.

Thanks for responses,

chuck