Several years ago, Richard McDougall wrote taztool - a GUI to display disk activity in an amazing and intuitive way. It used TNF trace data - a predecessor of DTrace.
In Janurary 2006 I began writing a DTrace version of taztool: DTraceTazTool. I wrote it using GTK and DTrace. Since then, the DTrace JNI has been released, and I've paused developing DTraceTazTool until I've taken a long look at Java 1.5. Until then, I'm releasing where I am at with the GTK/C version, on my DTrace website.
This is an alpha release - I'm still adding functionality, working through a todo list and fixing bugs. I'm releasing it early as it is already somewhat useful, and a great demo of DTrace. Probably the next feature I'll add is the ability to trace an entire disk at a time (rather than per-slice).
The following screenshot shows a UFS file system that was archived using the tar command. For the top plot: the requested block location is on the Y-axis, time is the X-axis, and the colour reflects the number of requests for that location (many == red). The bottom plot shows maximum and average seek distance.
DTraceTazTool already has some tunable options, such as the size of the pixels drawn and the sample rate,
DTraceTazTool needs to either run as root, or as a user with the dtrace_kernel privilege.
I hope you enjoy the tool so far. I'll post about updates as I complete them.
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