Solaris MPxIO is Oracle's Multi-pathing driver. 

It is controlled by the file /kernel/drv/scsi_vhci.conf.  The file has documentation on how to enable and disable the MPXIO as well as configure it for specific devices.

To disable MPXIO ensure that the mpxio-disable="yes"; is in the scsi_vhci.conf file.

The following command can be used to disable MPxIO. Consult Oracle related documentation for further guidance.
 

# stmsboot -d
 

To confirm if MPxIO is disabled, type:

# stmsboot -L
stmsboot: MPXIO disabled
 

MPxIO is not supported in Solaris LDOM (Oracle VM for SPARC) environments, I/O domains & LDOM guests
MPxIO is not supported when Veritas DMP_NATIVE_SUPPORT is enabled