Use the default AWS NVMe SSD for run farm instances

[abejgonzalez]

Background Work

• Yes, I searched the mailing list
• Yes, I searched the documentation

Feature Description

Instead of using /home/centos for AWS run farm hosts, we should instead mount the default SSD on the run farm machines and run simulations out of there (see https://serverfault.com/questions/952863/can-you-use-m5ds-local-ssd-as-a-root-device for the code to do this). This would require the run farm to have an extra hook to do any extra setup on the instance after launch run farm.

What I did after manually launching a runfarm, ssh'ing in, and setting up the SSD:

sudo mkdir -p /ssd
sudo mkfs.ext4 -E nodiscard -m0 /dev/nvme0n1
sudo mount -o discard /dev/nvme0n1 /ssd
sudo chown centos:centos -R /ssd/

Motivating Example

Faster writing simulations to disk.