a simple script for testing disk...

t_disk.sh

#!/bin/bash

if [ $# -lt 1 ]; then
    echo "usage:$0 dev"
    exit
fi

dev="$1"
echo "it will rw the dev:$dev, are you sure?[Y/n]"
read cmd

case "$cmd" in
    y|Y|Yes|yes)
        ;;
    *)
        exit 1
        ;;
esac

input="./time.input"
output="./time.output"

# write time into a temp file
while [ 1 ];
do
    time=`date +%s`
    echo "$time""k" > "$input"
    for((i=1;i<=250;i++));
    do
        echo "0" >> "$input"
    done

    # write
    dd if="$input" of=$dev bs=512 count=1 oflag=direct

    # read
    dd if=$dev of="$output" bs=512 count=1 iflag=direct
    
    diff "$input" "$output"
    ret=$?
    if [ $ret -ne 0 ]; then
        echo "It\'s different"
    fi

    sleep 1
done