root@downtown # iostat -xnzM 1
…
                   extended device statistics              
    r/s    w/s   Mr/s   Mw/s wait actv wsvc_t asvc_t  %w  %b device
    0.0    6.0    0.0    0.0  0.0  0.2    0.2   27.5   0  16 c1d0
    0.0    6.0    0.0    0.0  0.0  0.1    0.2   22.8   0  14 c2d0
    0.0    0.0    0.0    0.0  0.0 18446571229.3    0.0    0.0   0 1844657122934 md/d0
    0.0    0.0    0.0    0.0  0.0 18446559368.3    0.0    0.0   0 1844655936831 md/d20