https://metacpan.org/source/MARKWKM/Test-Parser-1.9/lib/Test/Parser/Iostat.pm

I thought it might be at least a model to steal code from, but it seems Test::Parser::Iostat uses a fixed set of columns

  push @{$self->{data}}, {device => $i[0], rrqm => $i[1], wrqm => $i[2
+],
            r => $i[3], w => $i[4], rmb => $i[5], wmb => $i[6], avgrq 
+=> $i[7],
            avgqu => $i[8], await => $i[9], svctm => $i[10], util => $
+i[11],
            elapsed_time => $self->{elapsed_time}};
[download]

and he suggest he has seen the cols change on different releases.