this only burns io on the root disk, what about the ephemeral disks or ebs mounts.  perhaps randomly pick from any mountpoint:
```bash
tmp=$(mktemp)
df -hl -x tmpfs | awk '/\//{print $6}' > $tmp
mount=$(sed -n $((RANDOM%$(wc -l < $tmp)+1))p $tmp)
rm $tmp
```
then the dd can b on of=$mount/burn