Try to saturate a hard-disk to check its capacity using standard Linux commands

saturate-disk.sh

#!/bin/env bash

target="$1"

if ! [ -d "$target" ]; then
    echo "Usage: $0 <directory>"
    exit 1
fi

#supposed capacity of the disk in GB
num_tbs=32000

gs=4
(("count = $num_tbs / $gs"))

for i in $(seq 1 "$count"); do
    of=$(printf "file-%05d" "$i")
    file="$target/$of"
    echo "writing ${gs}G to $file..."
    dd if=/dev/random of="$file" bs="$gs"G count=1
done