Problems about use DFSIO in hadoop 0.21.0

[Yingchao Liu]

Hello everyone,

Currently, I am trying to  run a benchmark to test the dataNode performance( 
write, append, read ). I think DFSIO is what I need, but I don't know how to 
use it, can anyone give me a line or tutorial to run DFSIO on hadoop-0.21.0?

thx