New is a mb.MetricSetFactory that returns a new MetricSet.

mapping fields which output by `iostat -x` on linux Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await r_await w_await svctm %util sda 0.06 0.78 0.09 0.27 9.42 8.06 48.64 0.00 1.34 0.99 1.45 0.77 0.03.

MetricSet for fetching system disk IO metrics.