delta = 5 sec;		// force evaluation once every 5 seconds from here on

// If for any disk, for all 4 samples (20 seconds), the disk is performing
// more than 40 I/Os per second, then print a message to standard output and
// then launch dkvis(1)
//
some_inst all_sample
    disk.dev.total @0..3 > 40 count/sec
	-> print "disks busy for 20 sec:" " %i" &
	   shell 5 min "dkvis";

// If any disk is performing more than 60 I/Os per second, then
// print a message identifying the busy disk to standard output and
// launch dkvis(1)
some_inst (
    disk.dev.total > 60 count/sec
) -> print "busy disks:" " %i" &
     shell 5 min "dkvis";