dd

For some interesting examples like creating ISO image or cloning a partition or disk wipe, read this article.

Test Disk I/O Performance with dd command

For more information visit these sites:

• cyberciti
• ArchLinux Wiki
• romanrm

Writing Speed

To test throuput (write speed):

dd if=/dev/zero of=/tmp/test1.img bs=1G count=1 oflag=dsync

To test latency:

dd if=/dev/zero of=/tmp/test2.img bs=512 count=1000 oflag=dsync

Reading Speed

For an accurate test you must clear the cache which requires root access:

echo 3 > /proc/sys/vm/drop_caches

then you can use dd to measure read speed:

time dd if=/path/to/bigfile of=/dev/null bs=8k