Section 4.14. Trace Normal Form (TNF) Tracing for IO

4.14. Trace Normal Form (TNF) Tracing for I/O

The TNF tracing facility was added to Solaris 2.5 release. It provided various kernel debugging probes that could be enabled to measure thread activity, syscalls, paging, swapping, and I/O events. The I/O probes could answer questions that iostat and Kstat could not, such as which process was causing disk activity. The probes could measure details such as I/O size, block addresses, and event times.

TNF tracing wasn't for the faint-hearted, and not many people learned how to interpret its terse output. A few tools based on TNF tracing were written, including the TAZ disk tool (Richard McDougall) and psio (Brendan Gregg).

For details on TNF tracing see TRacing(3TNF) and tnf_kernel_probes(4).

DTrace supersedes TNF tracing, and is discussed in the next section. DTrace can measure the same events that TNF tracing did, but in an easy and programmable manner.