CrystalDiskMark is a small HDD benchmark utility for your hard drive that enables you to rapidly measure sequential and random read/write speeds.
1000MB Files Test Benchmark on the My Passport Ultra 1TB:
On our ASUS UX31A Zenbook we found the WD My Passport Slim 1TB USB 3.0 portable drive reach 109 MB/s read and 108 MB/s write in the sequential test. Not bad performance numbers from a 5400 RPM notebook hard drive, but we are clearly limited by the hard drive and not the USB 3.0 interface.
ATTO is one of the oldest hard drive benchmarks that is still used today. ATTO measures transfers across a specific volume length. It measures raw transfer rates for both reads and writes and places the data into graphs that you can easily interpret. The benchmark was run with file sizes from 0.5kb through 8192kb with the total length being 256mb.
Benchmark Results: The WD My Passport Slim 1TB USB 3.0 drive hit 111 MB/s read and 110 MB/s write in ATTO, which is a popular benchmark in the storage community.