In any case I would test with tlp-stress or Cassandra stress tool any configuration
Sergio On Fri, Nov 1, 2019, 12:31 PM Ben Mills <b...@bitbrew.com> wrote: > Greetings, > > We are planning a Cassandra upgrade from 3.7 to 3.11.5 and considering a > change to the GC config. > > What is the minimum amount of memory that needs to be allocated to heap > space when using G1GC? > > For GC, we currently use CMS. Along with the version upgrade, we'll be > running the stateful set of Cassandra pods on new machine types in a new > node pool with 12Gi memory per node. Not a lot of memory but an > improvement. We may be able to go up to 16Gi memory per node. We'd like to > continue using these heap settings: > > -XX:+UnlockExperimentalVMOptions > -XX:+UseCGroupMemoryLimitForHeap > -XX:MaxRAMFraction=2 > > which (if 12Gi per node) would provide 6Gi memory for heap (i.e. half of > total available). > > Here are some details on the environment and configs in the event that > something is relevant. > > Environment: Kubernetes > Environment Config: Stateful set of 3 replicas > Storage: Persistent Volumes > Storage Class: SSD > Node OS: Container-Optimized OS > Container OS: Ubuntu 16.04.3 LTS > Data Centers: 1 > Racks: 3 (one per zone) > Nodes: 3 > Tokens: 4 > Replication Factor: 3 > Replication Strategy: NetworkTopologyStrategy (all keyspaces) > Compaction Strategy: STCS (all tables) > Read/Write Requirements: Blend of both > Data Load: <1GB per node > gc_grace_seconds: default (10 days - all tables) > > GC Settings: (CMS) > > -XX:+UseParNewGC > -XX:+UseConcMarkSweepGC > -XX:+CMSParallelRemarkEnabled > -XX:SurvivorRatio=8 > -XX:MaxTenuringThreshold=1 > -XX:CMSInitiatingOccupancyFraction=75 > -XX:+UseCMSInitiatingOccupancyOnly > -XX:CMSWaitDuration=30000 > -XX:+CMSParallelInitialMarkEnabled > -XX:+CMSEdenChunksRecordAlways > > Any ideas are much appreciated. >
