your V240 should have enough CPU to drive 1 of the 4 interfaces at 80MB/s.

I you are using a PCI riser card the it is 33Mhz 32/64 bits. This will cause 
slow performance but not as slow as you are getting. 

I would start by checking the throughput to your drives from the system level. 
This is actually the payload, the real numbers you are after. 

iostat -xnp 1 | grep rmt 

will give you a 1 second interval of the tape drives from the system 
perspective. 

 



Blaine Robison
Solaris Certified System Administrator
Solaris Certified Network Administrator 
Sun Certified Backup and Recovery Engineer
Veritas Certified Professional Data Recovery