SUMMARY: Phantom scsi disk in sar output (2)

From: John Horne (
Date: Fri Aug 18 2000 - 04:39:49 CDT

At the end of my previous summary I added a further question:

> As a side issue, I also noticed that on the older systems the CDROM drive
> has a target number of 6, but on the newer ones (our Ultra 10's) it
> defaults to target number 2. Any reason for this or is it another quirk
> coming from the fact that they are PCI based systems?

It was perhaps not really appropriate for me to do this since I should now
provide, I guess, a second summary :-) Better would have been to ask the
question seperately.

Anyway, thanks to those who replied. As a summary I am simply going to
include Ric Anderson's and Arthur Darren Dunham's answers since they pretty
much say it all. Needless to say if I actually thought about the problem
then it would have probably hit me that the difference was due to the
differing buses. Obviously you people are more on the ball than me...:-)

On 17-Aug-00 at 03:24:32 Ric Anderson wrote:
> The U-10s (300MHz) here use IDE disks. Typical PC dual channel IDE with
> 2 IDE devices per channel. The kernel sees them as
> c0t0d0 Primary IDE master drive (primary internal HD)
> c0t1d0 Primary IDE slave drive (secondary internal HD)
> c0t2d0 Secondary IDE master drive (CD-ROM)
> c0t3d0 Secondary IDE slave drive
> In practice, I've never seen c0t1d0 or c0t3d0, as we don't have any
> extra internal disks in the U10s.
> On systems with SCSI devices, c0t6d0 is the CD-ROM. Older systems use
> c0t3d0 as the default system device - less old ones use c0t0d0. E.G., the
> Ultra-60s we have at work use c0t6d0 for CD and c0t0d0 for boot. The old
> Sparc 5 and 20 boxes use c0t6d0 for CD-ROM and c0t3d0 for boot.

On 16-Aug-00 at 16:38:48 Arthur Darren Dunham wrote:
> Scsi generally puts disks at the bottom (0,1..), so they put the cdrom
> at the top (6),
> Your ultra10 is not scsi, but IDE. So the target numbers are different.

Many thanks,


John Horne, University of Plymouth, UK Tel: +44 (0)1752 233914
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