Re: rescan scsi

Peter Svensson (
Fri, 20 Jun 1997 18:55:28 +0200 (MET DST)

On Fri, 20 Jun 1997, Richard B. Johnson wrote:

> Nevertheless, it is possible. There is no existing kernel code to support
> this. You CAN swap drives that are identical by dismounting the existing
> one, removing it, hooking up the other, then remounting (after fsck).
> Basically you are tricking the kernel into thinking it's the same drive.

"How inconvenient it must be walking around with a foot in your mouth" ;-)
Yes, there _is_ code in the kernel to handle reprobing/dropping devices on
the fly. You really shouldn't swap two identical devices without notifying
the kernel, as there may be internal states kept.

> I use this trick on my Suns. When I boot a Sun, I hook up an external
> tape drive. Once it is "up", I disconnect the drive (I only have 1 to share
> over a bunch of Suns).

Under Solaris/Linux/NetBSD/OpenBSD at the very least you can reprobe
individual devices or whole buses during runtime, no need for such
trickery. In fact, most of the os:s really, _really_ dislikes having a
probed device removed on the fly without notification. Try accessing the
device after it has been removed and enjoy the console. :)