My immediate guess: your transaction logs are on the same media as your sstables and your OS prioritizes read requests.
-Jeff > On Jul 23, 2015, at 2:51 PM, Soerian Lieve <sli...@liveramp.com> wrote: > > Hi, > > I am currently performing benchmarks on Cassandra. Independently from each > other I am seeing ~100k writes/sec and ~50k reads/sec. When I read and write > at the same time, writing drops down to ~1000 writes/sec and reading stays > roughly the same. > > The heap used is the same as when only reading, as is the disk utilization. > Replication factor is 3, consistency level on both reads and writes is ONE. > Using Cassandra 2.1.6. All cassandra.yaml settings set up according to the > Datastax guide. All nodes are running on SSDs. > > Any ideas what could cause this? > > Thanks, > Soerian
