Cassandra os-tuning.

OS TUNING - Cassandra

Below settings should be applied to all node of Cassandra cluster.

File Descriptors : Cassandra needs more file descriptor than default settings of 1024, below is how you can change it.

#echo "* soft nofile 32768" | sudo tee -a /etc/security/limits.conf

#echo "* hard nofile 32768" | sudo tee -a /etc/security/limits.conf

#echo "root soft nofile 32768" | sudo tee -a /etc/security/limits.conf

#echo "root hard nofile 32768" | sudo tee -a /etc/security/limits.conf

User Resource Limits :

Added the following entries in /etc/security/limits.conf file.

# End of file

* soft nofile 32768

* hard nofile 32768

root soft nofile 32768

root hard nofile 32768

* soft memlock unlimited

* hard memlock unlimited

root soft memlock unlimited

root hard memlock unlimited

* soft as unlimited

* hard as unlimited

root soft as unlimited

root hard as unlimited

Run command

#sysctl -w vm.max_map_count=131072

Disable Swap - Lets not jvm gets swapped rather get it killed by oom killer. As even swapped jvm eventually will killed by oom. Better node to down then slow.

# sudo swapoff --all

Synchronize Clocks : The column will only get overwrite if recent version has latest time compare to old value.

NTP is already running on server