if you mean "hadoop does not give a speed-up compared with a sequential version" then this is because of overhead associated with running the framework: your job will need to be scheduled, JVMs instantiated, data copied, data sorted etc etc.
if your jobs can be parallelised and you have enough machines (your cluster is large enough) then the ability to use more machines should compensate for the framework overhead. even if your sequential / hacked version running on a small cluster beats the hadoop version, in my mind a major advantage of Hadoop (and this is something that people tend to forget) is that your Hadoop version almost certainly will be simpler and easier to maintain. Miles 2009/5/21 zhu hui <chinazhuhu...@gmail.com>: > hello, everybody. > > i am fresh to hadoop, and i heard from others that hadoop performs not > efficient when the cluster is very small,for example 6 machines. > > but i cannot find out the reasons and materials that i can make them as the > proofs. > > thanks very much if anybody who can share me with some materials or ideas. > > Best Wishes. > > Eric.Syu > > -- > Nothing Impossible > -- The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.
