The following recommendations are for production environments. You may need to adjust them accordingly for your implementation.
Cassandra generally needs more than the default amount (1024) of file descriptors. To increase the number of file descriptors, change the security limits on your Cassandra nodes. For example:
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
For more information, see Java reports an error saying there are too many open files.
Cassandra requires greater user resource limits than the default settings. Add the following entries to your /etc/security/limits.conf 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
In addition, you may need to be run the following command:
sysctl -w vm.max_map_count = 131072
The command enables more mapping. It is not in the limits.conf file.
On CentOS, RHEL, OEL Sysems, change the system limits from 1024 to 10240 in /etc/security/limits.d/90-nproc.conf and then start a new shell for these changes to take effect.
* soft nproc 10240
For more information, see Insufficient User Resource Limits Errors.
Disable swap entirely. This prevents the Java Virtual Machine (JVM) from responding poorly because it is buried in swap and ensures that the OS OutOfMemory (OOM) killer does not kill Cassandra.
sudo swapoff --all
For more information, see Nodes seem to freeze after some period of time.
The clocks on all nodes should be synchronized using NTP (Network Time Protocol).
This is required because columns are only overwritten if the timestamp in the new version of the column is more recent than the existing column.
Typically, a setra of 512 is recommended, especially on Amazon EC2 RAID0 devices.
Check to ensure setra is not set to 65536:
sudo blockdev --report /dev/<device>
To set setra:
sudo blockdev --setra 512 /dev/<device>