We're running an insert-heavy use-case and have set "durable_writes = false" for all of our keyspaces. While inserts are coming in (about 2000 1k-records per second), we are still seeing 50Mb written to files in the commitlog directory every 6-10 seconds (using iostat).
Anybody know why so much data would written in this situation? We're guessing that these writes are related to the system and system_traces keyspaces, right? Is it considered ok to turn off durable_writes on those keyspaces? (I couldn't find anything on this searching the message board or google).
(Note we have double- and triple- checked that all of our keyspaces definitely have durable_writes=false, with multiple clean-and-restarts of cassandra)