Elasticsearch uses a hybrid mmapfs / niofs directory by default to store its indices. The default operating system limits on mmap counts is likely to be too low, which may result in out of memory exceptions.
On Linux, you can increase the limits by running the following command as root:
sysctl -w vm.max_map_count=262144
To set this value permanently, update the vm.max_map_count setting in /etc/sysctl.conf. To verify after rebooting, run sysctl vm.max_map_count.
The RPM and Debian packages will configure this setting automatically. No further configuration is required.