Use AWS until you have a reasonable grasp of your dataset and real requirements. Then buy whatever provides the best bang for your buck, in terms of servers. Th

Use AWS until you have a reasonable grasp of your dataset and real requirements. Then buy whatever provides the best bang for your buck, in terms of servers. That will probably mean getting 6 mid-range servers, rather than the three servers with the absolute fastest CPU/most memory available. Use either RedHat (CentOS) or Debian, and you'll almost certainly be using Hadoop. Dell servers are fine, although you can sometimes save significantly by going with something like Supermicro servers from Newegg. In terms of cost, you'll want to order the bulk of your servers' memory from a third-party, not have it included in the build.