EBS disk warming script using fio

ebs_warm_disk.sh

#!/usr/bin/env bash
# EBS disk warming script to run on boot to automatically warm restored snapshot
# disks once per volume id
# Place entry in crontab for root using `crontab -e`
# ### Note some paths are restrictive and require extra workarounds
# PATH=/sbin:/usr/local/bin:/bin
# @reboot bash -c "sleep 60 && ebs_warm_disk >> /var/log/fio.log 2>&1"

# Assumptions
# volume to warm is /data and xfs type

set -eou pipefail
set -x

readonly FIO_COMPLETED="${FIO_COMPLETED:-/data/fio.completed}"
readonly FIO_LOG="${FIO_LOG:-/var/log/fio.log}"
readonly FIO_LOCK_FILE="${FIO_LOCK_FILE:-/data/fio.lock}"
declare fio_bin
declare ebsnvme_bin

fio_bin="$(which fio)"
ebsnvme_bin="$(which ebsnvme-id)"

# Use 200mb as the rate since that can be tolerated by most/all drives in our network
# with these settings it works out to be 1600 iops
function run_fio() {
  local device="$1"
  sudo "$fio_bin" --status-interval=60 --eta-newline=60 --filename="$device" --rw=read --bs=128k --iodepth=64 --ioengine=libaio --direct=1 --name=volume-initialize --rate=200m 2>&1 | sudo tee -a "$FIO_LOG"
  echo "$volumeId" > "$FIO_COMPLETED"
}

function main() {
  local device
  local volumeId
  device="$(grep '/data xfs' < /proc/mounts | awk '{print $1}')"
  volumeId="$(sudo "${ebsnvme_bin}" "$device" | awk -F': ' '{print $2}')"

  # when fio completes create /data/.fio.complete that contains the volume-id

  if [[ ! -f "$FIO_COMPLETED" ]]; then
    # missing fio completion file, needs warming
    run_fio "$device"
  elif ! grep "$volumeId" < "$FIO_COMPLETED" ; then
    # file present but lacks the correct volumeid
    run_fio "$device"
  else
    # no warming needed
    echo "ebs volume ${device} already warmed"
  fi
}

{
  # Exit if cannot acquire exclusive lock
  flock --nonblock -x 42 || exit 1
    main
} 42>"$FIO_LOCK_FILE"