PV 114X no longer recognized by the OS

I have a PV114X that we had working under both RedHat 6 and Solaris 11. Both recognized the device and worked right out of the box with a fresh OS install.  Now neither fully recognize the device. Solaris consistently sees the device on a SCSI scan as evident in the dmesg output but /dev/rmt/0 is not created. RH saw the device in the initial OS install, created /dev/st0 and also returned output on an 'mt -f /dev/st0 status' command. However, when I issued a 'tar -tfv /dev/st0' it returned an I/O error and never recognized the device again on subsequent reboots even though there was an entry in the SCSI table for the device.

I find this very odd since there are two drives in this unit, each on separate SCSI chains. There are two SAS ports on each drive.  I am pretty sure one is for input and the other for chaining but there is no documentation specifying this. Which one is the input? There are no markings on the port.

How can I troubleshoot this further?