Dear all, So, here is our setup so far:
- Ubuntu 12.04 - Cassandra 2.0.10, JDK 1.7.0_65-b17 - 6 nodes (EC2 c3.8xlarge/ 32 cores/60GB RAM, EBS disks for data, ephemeral SSD for commit logs etc) - pretty heavy write load - 100Ks/second - RF=2, one dc, 2 racks - everything works just fine with low CPU consumption - load average tends to be around 4-10 Now, we are trying to add a node. This cases a heavy load on existing nodes - like over 100 load average. The cluster becomes unresponsive, writes and reads mostly fail. The weird observations are that: - without adding new node CPU is low - if we turn off writes while adding a new node load average on existing nodes drops back to 4-10 and the new node just fine I've checked VisualVM sampling and basically all the CPU on existing nodes is consumed by org.jboss.netty.channel.socket.nio.SelectorUtil.select(). What we tried so far: - throttling streaming - no impact - disabling internode compression - no impact - disabling autocompaction on existing nodes - no impact - even running with -Dorg.jboss.netty.epollBugWorkaround=true - no impact And as of now we are somewhat desperate as this behavior is a blocker for us - we can't afford losing writes and we will need to expand C* dynamically. Anyone has encountered something similar? Any ideas/hints? Thanks
