Re: Two SCSI bus question...

Christoph Doerbeck (
Tue, 09 Dec 1997 15:57:21 -0500

> > The topic of having multiple SCSI buses has surfaced before, but
> > my curiousity is how the /dev/(scanner) is assigned to a device.
> > SCSI disks are simple, they're assigned in the order that they
> > are detected (unless configured otherwise in the kernel). But,
> > my scanner device seems to waffle around depending on whether or
> > not some other devices are turned on/off at boot time. Any ideas???
> All detected devices are assigned a raw-device in the order in which they
> are detected. Scanning the busses goes dev-id first, then bus-id.
> Thus you first get all devices on the first bus, then all on the second,
> each in order of the SCSI IDs.
> Thus your scanner wanders whenever a device that is below it in that ordering
> scheme is there or not.

But, let's say I have disk 1 (id=0), disk 2 (id=1), tape drive (id=2) and disk
3 (id =3). Isn't disk 3 always /dev/sdc regardless if the tape drive powered
up? Let's say disk 4 is on controller 2 as id=0. Now /dev/sdd is always
/dev/sdd unless one of the previous disks is not present at power up,
of the state of the tape drive.

Shouldn't the scanner device behave the same way???? :-(

Maybe I'll just revert to the old ways of compiling device entries into the

- Christoph

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