Price the cost of 1GbE->10GbE vs. more nodes, using data from monitoring your cluster during peak load. It should be clear which is a better value.
Russ On Tue, Jun 28, 2011 at 4:05 PM, Mathias Herberts < [email protected]> wrote: > On Wed, Jun 29, 2011 at 01:02, Matei Zaharia <[email protected]> > wrote: > > Ideally, to evaluate whether you want to go for 10GbE NICs, you would > profile your target Hadoop workload and see whether it's > communication-bound. Hadoop jobs can definitely be communication-bound if > you shuffle a lot of data between map and reduce, but I've also seen a lot > of clusters that are CPU-bound (due to decompression, running python, or > just running expensive user code) or disk-IO-bound. You might be surprised > at what your bottleneck is. > > From my experience, jobs that shuffle lots of data are also very often > slowed down by the sort phase, compressing mappers' output is a first > step to improve performance. Given the cost of a 10GbE infrastructure > with no oversubscription I'd monitor bandwith usage very closely prior > to investing in that kind of network gear. >
