dio is a new Solaris utility. It is a device I/O analysis tool that lets users visualise data flow in a way that has so far been unavailable. dio is ideal for analysing slow I/O devices, or just to get a handle on how the device is being used. It can work against an partition, a disk or a metadevice. It totals the data transfer through the device as it runs to give a useful overall usage.
dio was only released very recently but has so far been very well received by the Solaris community. It is available at http://www.diodio.org/, where you will find precompiled binaries, standard Solaris packages and the GPL licensed source.