I think it has more than double the load. It is double the data. More read repair chances. More load can swing it's way during node failures etc.
On Wednesday, February 15, 2017, Benjamin Roth <benjamin.r...@jaumo.com> wrote: > Hi there, > > Following situation in cluster with 10 nodes: > Node A's disk read IO is ~20 times higher than the read load of node B. > The nodes are exactly the same except: > - Node A has 512 tokens and Node B 256. So it has double the load (data). > - Node A also has 2 SSDs, Node B only 1 SSD (according to load) > > Node A has roughly 460GB, Node B 260GB total disk usage. > Both nodes have 128GB RAM and 40 cores. > > Of course I assumed that Node A does more reads because cache / load ratio > is worse but a factor of 20 makes me very sceptic. > > Of course Node A has a much higher and less predictable latency due to the > wait states. > > Has anybody experienced similar situations? > Any hints how to analyze or optimize this - I mean 128GB cache for 460GB > payload is not that few. I am pretty sure that not the whole dataset of > 460GB is "hot". > > -- > Benjamin Roth > Prokurist > > Jaumo GmbH · www.jaumo.com > Wehrstraße 46 · 73035 Göppingen · Germany > Phone +49 7161 304880-6 · Fax +49 7161 304880-1 > AG Ulm · HRB 731058 · Managing Director: Jens Kammerer > -- Sorry this was sent from mobile. Will do less grammar and spell check than usual.
