Multithreaded Read & Write Patterns

The multithreaded tests simulate a situation when there are one to four clients accessing the virtual disk at the same time, the request queue depth varying from 1 to 8. The clients’ address zones do not overlap. You can click the links below for full test results, but we will only discuss diagrams for a request queue of 1 as the most illustrative ones. When the queue is 2 or more requests long, the speed doesn’t depend much on the number of applications.

• IOMeter: Multithreaded Read
• IOMeter: Multithreaded Write

When there is only one read thread to be processed, the results depend on the drives’ sequential speeds. The 3.5-inch models have no rivals then while the previous-generation 2.5-inchers with low-density platters are on the losing side. When a second thread is added, Western Digital’s 2.5-inch drives (they have very similar firmware) and the Seagate 7200.3 take the lead. The same goes for three read threads. When there are four threads, WD’s Caviar Blue loses its ground while the Seagate 7200.11 accelerates and takes second place. It is nice to see Seagate’s newer drives have got rid of the common problem of Seagate’s older products – an awful performance at multithreaded reading. The Seagate Momentus 7200.2 is a striking example of that problem.

As opposed to the Seagate 7200.11, the WD Caviar Blue maintains a high speed at multithreaded writing. The new 2.5-inch products are good here and compete for second and third places.