Solving Redis warnings on overcommit_memory and Transparent Huge Pages for Ubuntu 16.04 on EC2
On a fresh Ubuntu 16.04 EC2 instance the warnings appear like so:
WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.
WARNING you have Transparent Huge Pages (THP) support enabled in your kernel. This will create latency and memory usage issues with Redis. To fix this issue run the command 'echo never > /sys/kernel/mm/transparent_hugepage/enabled' as root, and add it to your /etc/rc.local in order to retain the setting after a reboot. Redis must be restarted after THP is disabled.
How to eliminate them permanently?
Answer
Like the warning suggests, just add the line vm.overcommit_memory=1 to the bottom of /etc/sysctl.conf, with something like sudo vi /etc/sysctl.conf.
But permissions don't allow you to edit THP as the warning suggests, so instead do
sudo apt install hugepages
and add the command sudo hugeadm --thp-never to the bottom of your .bashrc, with something like sudo vi ~/.bashrc.
Then just sudo reboot and next time you SSH in run redis-server and the warnings are gone!