disk benchmark utility
Download from PortableApps.com
CrystalDiskMark Portable can run from a cloud folder, external drive, or local folder without installing into Windows. It's even better with the PortableApps.com Platform for easy installs and automatic updates.
CrystalDiskMark can measure sequential reads/writes speed, measure random 512KB, 4KB, 4KB (Queue Depth=32) reads/writes speed, has support for different types of test data (Random, 0Fill, 1Fill), includes basic theme support and has multilingual support (though it will not yet remember your language selection between runs).