Another addition to DTrace was the integration of a SCSI provider allowing you to trace SCSI commands on your system. It’s a quite powerful feature allowing you to get in-depth insight what’s going on on the storage side of your system. I really suggest to read through the documentation.
However what’s not really highlighted in the “What’s new” documentation for Solaris 11.4 is the availability of a new script called scsitrace in Oracle Solaris 11.4. This script uses the new functionality in order give you this kind of deep insight without having to write a script for DTrace on your own.
This script would have been really handy recently when i had to diagnose a performance problem at a customer. I got the data differently, but it would have been much easier with the script. However the system was still running 11.3.