🚀 go-pugleaf

news1@bgcomp.co.uk wrote:

> Paul Black <paul.black@oxsemi.com> wrote:
> > Robin <ng@rszemeti.demon.co.uk> wrote:
> >>
> >> So busy on here .;-)
> >>
> >> but I you always get a quality answer I find ..
> >>
> >> anyway ..
> >>
> >> say you boot your machine and you don't happen to have your nice SCSI
> >> scanner turned on ..
> >>
> >> Is there some mysterious incantation to get the SCSI bus grepped again
> >> and my now
> >> happily waiting scanner recognised .. or do I really have to do the
> >> poweroff thing ??
> 
> > I'll assume you're using Linux because a) the header files of your
> > message and b) it's the only one I can answer for :-)
> 
> > You need to be using SCSI as a module (and not compiled into the
> > kernel). Unload the SCSI module (you would need to unmount SCSI disks
> > and unload the modules for all the SCSI devices). Reload the modules as
> > necessary. When the SCSI module is loaded it scans the bus. (This worked
> > for me in the past when I forgot to plug in a tape drive).

> 
> Suse Linux has the script rescan-scsi-bus.sh which should do the
> business. Other distro's may also have it.

I can't find it on Red Hat 6.2. Unloading and reloading the module
doesn't sound particularly practical if your root disk happens to be
SCSI as mine is (I don't think I'll test this:). As it is a script it
must call some programs - what are they? Is the script short enough to
post? 

Of course it is generally regarded as a bad idea to power on/off
peripherals with the machine running. I once experienced a terrible
problem when the night shift failed to turn off the power on all the
devices after a UPS failure (it exploded - literally:) and allowed the
machines and their external SCSI disks to come up together, generating a
race condition. Of course a scanner will be a lot more benign than that
but even so it is not really recommended.

Regards, Ian