Hello All,

We have seen many times where a custom sd.conf file prevents the system 
(Solaris 2.x) from seeing tape drives.

Example:

an entry commented out in sd.conf for target 3, lun 0 prevents a tape drive 
from being seen at this target and LUN.

another example would be any entry that specifies a parent, hba or wwn. So in 
the above instance if the line wasn't commented out but rather had a line that 
also specified something like:

name="sd" class="scsi" target=2 hba="fcaw3" lun=0;

Unless there were an entry like this for hba="fcaw0" a drive on fcaw0 at the 
same target and lun would not be seen.

It seems to me that the st driver requires the sd driver for scsi access or at 
minimum relies on the sd driver to "probe" for scsi devices.

Many people have argued this point with me but I have seen this behavior too 
many times ... the sd driver definately has an affect on tape drive visibility.

When you look at the man page for sd, it says "sd - SCSI disk and ATAPI/SCSI 
CD-ROM device driver".

Has anyone else witnessed this behaviour?

If so, does anyone have a clear understanding of how the two work together?

By what I have observed, im visualizing some kind of abstraction like this:


tape drive
--------------
Fibre(JNI)
---------------
fcaw driver
---------------
sd driver
---------------
st driver
---------------
kernel
---------------
ioctl() system calls to control tape device

Does it really work this way?

I looked around in the Solaris source code and could not find the sd or the st 
driver anywhere, does anyone know where I can find them?

TIA

--Buddy