Benchmark Block Devices (SD cards, USB sticks, drives etc)

blockdevicetest.sh

#!/bin/bash

if [ "$#" -lt 3 ]; then
    echo "Usage: $0 mode device block_size1 [block_size2 ...]"
    echo "Example: $0 read /dev/rdisk2 1m 4m 8m 16m"
    exit 1
fi

# Request sudo upfront
if ! sudo -v; then
    echo "This script requires sudo privileges"
    exit 1
fi

mode=$1
if [ "$mode" != "read" ] && [ "$mode" != "write" ]; then
    echo "Invalid mode. Please use either 'read' or 'write'"
    exit 1
fi

device=$2
if [ ! -b "$device" ]; then
    echo "Invalid input device"
    exit 1
fi
shift 2

# Function to convert block size to bytes
get_bytes() {
    local size=$1
    local number=${size%[cwbkKmMgG]}
    local suffix=${size#"$number"}
    
    case $suffix in
        c) echo $((number * 1));;
        w) echo $((number * 2));;
        b) echo $((number * 512));;
        k) echo $((number * 1024));;
        K) echo $((number * 1000));;
        m) echo $((number * 1024 * 1024));;
        M) echo $((number * 1000 * 1000));;
        g) echo $((number * 1024 * 1024 * 1024));;
        G) echo $((number * 1000 * 1000 * 1000));;
        *) echo $number;;  # Assume bytes if no suffix
    esac
}

# Function to format bytes to human readable
format_bytes() {
    local bytes=$1
    if [ $bytes -ge $((1024 * 1024 * 1024)) ]; then
        echo "$(echo "scale=2; $bytes/1024/1024/1024" | bc)GB"
    elif [ $bytes -ge $((1024 * 1024)) ]; then
        echo "$(echo "scale=2; $bytes/1024/1024" | bc)MB"
    elif [ $bytes -ge 1024 ]; then
        echo "$(echo "scale=2; $bytes/1024" | bc)KB"
    else
        echo "${bytes}B"
    fi
}

# Store results in a file for easier sorting
results_file=$(mktemp)

for bs in "$@"; do
    # Convert block size to bytes
    bs_bytes=$(get_bytes "$bs")
    
    # Calculate number of blocks to transfer approximately 1GB
    target_bytes=$((1024 * 1024 * 1024))
    blocks=$((target_bytes / bs_bytes))
    total_bytes=$((blocks * bs_bytes))
    
    formatted_size=$(format_bytes $total_bytes)
    echo "Testing ${bs} blocks | data transfer: ${formatted_size}"
    sudo purge
    echo "----------------"
    
    start_time=$(date +%s)
    if [ "$mode" == "read" ]; then
        sudo dd if=$device of=/dev/null bs=$bs count=$blocks status=progress
    else
        sudo dd if=/dev/zero of=$device bs=$bs count=$blocks status=progress
    fi
    end_time=$(date +%s)
    duration=$((end_time - start_time))
    
    # Store each result as: duration block_size transfer_size
    echo "$duration $bs ${formatted_size}" >> "$results_file"
    
    echo "----------------"
    sleep 5
done

echo ""
echo "--------------------------------"
echo "Results from fastest to slowest:"
echo "--------------------------------"
sort -n "$results_file" | while read -r duration bs transfer; do
    echo "Block size: ${bs} | Transfer: ${transfer} | Time: ${duration}s"
done

rm "$results_file"