Below is a simple script to test filesystem read/write performance using dd with varying blocksize parameter. This can be useful for testing local filesystems as well as network-mounted filesystems. The end result will be a CSV file that can be opened and graphed using your favorite spreadsheet application.

#!/bin/ksh
# krazyworks.com
# Run filesystem performance test using dd with varying block size parameter
#

if [ ! $1 ] || [ ! $2 ] ; then echo "Usage: ddtest [filesize in GB] [target directory]" ; exit 1 ; fi
filesize=$1 ; target1=$2 ; target=$(echo "${target1}" | sed 's@/$@@g')

if [ ! -d "${target}" ] ; then echo "Usage: ddtest [filesize in GB] [target directory]" ; exit 1 ; fi
if [ ! -w "${target}" ] ; then echo "Directory ${target} is not writable by `/usr/bin/whoami`" ; exit 1 ; fi

outfile="/tmp/ddtest_`hostname -s`_`date +'%Y-%m-%d_%H%M%S'`.csv"
if [ -f "${outfile}" ] ; then /bin/rm -f "${outfile}" ; fi

mountpoint=$(df -hP "${target}" | grep -v ^Filesystem | awk '{print $1}')
host=$(hostname -s)

cat << EOF
${host}
`date +'%Y-%m-%d %H:%M%'`
---------------------------------------------------------------------
Testing ${target} mounted on ${mountpoint}

EOF

echo "Date,Host,Run,Direction,Rate,Unit,Filesize (Bytes),Blocks,Block Size (Bytes),Target,Mountpoint" | tee -a "${outfile}"

filesize_b=$(echo "scale=0;${filesize}*1024*1024*1024"|bc -l)

for blocksize in 1048576 2097152 4194304 8388608 16777216
do
	for i in `seq 1 5`
	do
		timestamp=$(date +'%Y-%m-%d %H:%M:%S')
		blockcount=$(echo "scale=0;${filesize_b}/${blocksize}"|bc -l)
		line=$(dd if=/dev/zero bs=${blocksize} count=${blockcount} of=${target}/ddtest_${host}.tmp 2>&1)
		speed=$(echo "${line}" | grep "/" | awk '{print $8","$9}')
		echo "${timestamp},${host},${i},up,${speed},${filesize_b},${blockcount},${blocksize},${target},${mountpoint}" | tee -a "${outfile}"
		if [ -f /tmp/ddtest_${host}.tmp ] ; then /bin/rm -f /tmp/ddtest_${host}.tmp ; fi
		timestamp=$(date +'%Y-%m-%d %H:%M:%S')
		line=$(dd if=${target}/ddtest_${host}.tmp bs=${blocksize} count=${blockcount} of=/tmp/ddtest_${host}.tmp 2>&1)
		speed=$(echo "${line}" | grep "/" | awk '{print $8","$9}')
		echo "${timestamp},${host},${i},down,${speed},${filesize_b},${blockcount},${blocksize},${target},${mountpoint}" | tee -a "${outfile}"
	done
done