>No reply anyone???
>How does the SG driver work? Doesn't it need to talk through the st driver
>to get its work done?

OK, I'll bite. 

No. 'sg' (SCSI generic) does not use 'st' (SCSI tape). sg attaches itself to 
every HBA driver of the class scsi. sg is a pass thru driver: It allows 
userland applications to pass scsi commands to arbitrary scsi devices, just 
like Solaris' own USCSI interface.

IBMtape is a replacement for 'st'. So, even if you have IBMtape, you still 
need 'sg' for various purposes: serialization of devices and I believe that 
also reserve/release is done via 'sg'.

To rave on about the use of IBMtape: Why use it? 
 - VERITAS does not support it
 - SUN does not support it
 - You have trouble with it
What's the advantage of IBMtape over st?
 
SUN's policy is that there is 'st' support for every tape drive that SUN 
ships/resells with proper defaults (like variable block length). 

Sure there is support for LTO-1 and LTO-2 for IBM, HP and Seagate. Just 
install the latest 'st' patch for your OS and your set. There is really no 
need to modify st.conf if you have the latest 'st'. 

The current 'st' patches are:
 Solaris 2.6    105505-16
 Solaris 7      107461-14
 Solaris 8      108725-13
 Solaris 9      113277-12

Best regards, 

Joost
-- 
Long may you run.