Why do controllers differ between physical and logical names

UNIX Solaris
1

When I look at format I can see the following info:

AVAILABLE DISK SELECTIONS:
       0. c1t0d0 <SUN72G cyl 14087 alt 2 hd 24 sec 424>
          /pci@1c,600000/scsi@2/sd@0,0
       1. c1t1d0 <SUN72G cyl 14087 alt 2 hd 24 sec 424>
          /pci@1c,600000/scsi@2/sd@1,0

Can anyone tell me why the logical name shows the disks on controller 0 but the physical shows then on controller 2?

Thanks in advance.

2

c1 is the second controller in the system...

3

The "2" in "scsi@2" is a bus or slot id and is a physical characteristic of the hardware. It has nothing to do with the controller number which is assigned when the hardware is detected the first time.

"scsi@2" is most likely the address of the internal scsi controller, whereas the external scsi controller would be "scsi@2,1". If you connect a storage box to the external scsi port you might get disk names like c2t0d0, c2t0d1, ...