In these pre-OOW 2013 days, everyone is excited about new features of Oracle 12c. This post describes particularly interesting one – IO outliers profiling in V$KERNEL_IO_OUTLIER.
According to Oracle Documentation and Glenn Fawcett blog we know that V$KERNEL_IO_OUTLIER uses the DTrace to collect information about the amount of time an IO spends in operating system components. DTrace is the Solaris dynamic tracing tool which allows to observe all OS activity.
V$KERNEL_IO_OUTLIER should provide an operating system-based latency breakdown of IO taking an excessive amount of time to complete. This will be essential diagnostics feature. But, many people complained that V$KERNEL_IO_OUTLIER is always empty. This was enough for me to start investigating it.
I will discuss the view, when and how it works, the underlying DTrace script and how it can be used for pre-12c Oracle.