UNIX for Dummies Questions & Answers

Hi All,

I have a question.

/pci@1f,4000/scsi@3/disk is one of my device name.

The scsi@3 stands for SCSI id - 3. ( Is that Correct ?) . But the
disk alias points to /pci@1f,4000/scsi@3/disk@0,0 ( that is target 0 )

What is the significane of SCSI@3, when all devices are having individual scsi target ids..

Hope somebody will clarrify my doubt.


[ I have searched the forum, but I couldn't get the answer ]

pls state what variant of unix / kernel are you using. The best if you could uname -a and post it in the Thread. SCSI configuration is quite vary in most of unix'es.

Hi,

Sorry I missed that information in my thread.

The machine is Ultra Sparc 30, sun4u architechture, Sun OS 5.5.1

Ok your ID could be from the range 0 to 7. The host adapter was always ID 7, so that left to you 0 to 6. Most PC operating systems wanted ID 0 as the boot drive (and most still do). HP machines would boot from the highest ID, Sun would boot from 3 but pretend it was 0, and so on. With SCO, there was no question: you booted from ID 0.

Wide devices now have ID's 0 to 15. The host adapter still usually gets the 7 slot, and it's still easier to set the boot disk to 0 for SCO and most other OS's.

The ID is usually set with jumpers or switches. These are often labeled (on the narrow devices) ID0, ID1, ID2. The values are binary; if ID0 is jumpered or turned on that's a "1", if ID1 is on that's "2", and if ID2 is on that's "4". By combining jumpers you can set any value from 0 to 7. For example, to get ID 5, you'd jumper ID0 and ID2. To get 3, you'd jumper ID0 and ID1, and for 6 you'd jumper ID1 and ID2

Hope this clarify your doubts.

Ok that was a good information. But my question was,

Even if scsi id is ' 0 ' for my disk, the full device name appears as

/pci@1f,4000/scsi@3/disk@0,0
and for the cdrom,
/pci@1f,4000/scsi@3/disk@6,0:f
and for the dat drive
/pci@1f,4000/scsi@3/disk@5,0

I assume scsci@3 is the scsi id. ( I read in one of the unix books. ).

What do we understand by SCSI@3 ?. Does this mean a primary scsi channel ?

I'm sure this is not the target id. Here the target IDs appeared correctly just after disk@

Here is the probe output on one of my Server running on a raid SCSI disk:

disk0 /pci@1f,4000/scsi@3/disk@0,0
disk1 /pci@1f,4000/scsi@3/disk@1,0
disk2 /pci@1f,4000/scsi@3/disk@2,0
disk3 /pci@1f,4000/scsi@3/disk@3,0
disk4 /pci@1f,4000/scsi@3/disk@4,0
disk5 /pci@1f,4000/scsi@3/disk@5,0
disk6 /pci@1f,4000/scsi@3/disk@6,0
tape0 /pci@1f,4000/scsi@3,1/tape@4,0
tape1 /pci@1f,4000/scsi@3,1/tape@5,0

it seems that the /scsi@3 is fixed. Its something like what they call as Parameter for your example called as" SCSI ID 3". Does this mean a primary scsi channel ? Yes, probarbaly your system detect it as a primary SCSI.

Thank You.