3.3     Slow all SCSI ports to asynchronous operation.
  
        For all other fast SCSI hosts attaching devices that do not
conform with the fast SCSI requirements, the operating system
should be modified to run all SCSI ports in asynchronous mode.
This slower mode fully interlocks all the SCSI data transfer
signals and provides for reliable operation of the Extended
Storage Module at the end of a SCSI bus.  It allows Sun
configurations containing both fast SCSI drives and
nonconforming devices to operate reliably on fast SCSI ports.

If the system configuration meets the standard SCSI
requirements,  reliable operation can usually be provided
with third-party components and peripherals as well.  The
slower data rate applies to all SCSI ports on the system.  Some
applications may show a decrease in performance because of the
slower data rate.

     For 4.1.x. OS:
  
                 To change to the slower asynchronous data rate, type:

                         adb -w /vmunix
           scsi_options?W 58
                         $q    
                        
         then reboot the system.

To turn synchronous transfer back on at the
highest possible speed, use the same procedure,
replacing the middle line with:

scsi_options?W 178

      For Solaris 2.x:

To change to the slower asynchronous data rate,
                add the following line to /etc/system file:
  
            set scsi_options = 0x58
  
              then reboot the system.
  
To turn synchronous transfer back on at the
highest possible speed without using tagged
queueing, change the scsi_options line to:

set scsi_options = 0x178

To turn synchronous transfer back onat the
highest possible speed allowing tagged queueing
(if available in the operating system),
change the scsi_options line to:

set scsi_options = 0x1f8