You get more latency on reads so overall execution time is longer Le 3 déc. 2016 7:39 AM, "kant kodali" <kanth...@gmail.com> a écrit :
> > I wonder what benefits do I really I get If I colocate my spark worker > process and Cassandra server process on each node? > > I understand the concept of moving compute towards the data instead of > moving data towards computation but It sounds more like one is trying to > optimize for network latency. > > Majority of my nodes (m4.xlarge) have 1Gbps = 125MB/s (Megabytes per > second) Network throughput. > > and the DISK throughput for m4.xlarge is 93.75 MB/s (link below) > > http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/EBSOptimized.html > > so In this case I don't see how colocation can help even if there is one > to one mapping from spark worker node to a colocated Cassandra node where > say we are doing a table scan of billion rows ? > > Thanks! > >
