Multi-Threaded Read & Write Patterns

The multi-threaded tests simulate a situation when there are several (from one to four) clients accessing the drive at the same time and the drives are processing requests for reading or writing 64KB data blocks for 30 seconds. The depth of the outgoing request queue is varied from 1 to 8.

We built diagrams for the case with the shortest request queue. It is the most common situation in practice.

The first diagram shows the speed of multi-threaded reading. The Samsung SpinPoint M60S HM120JI is the best of the three HDDs we’re interested in. It doesn’t slow down much as the number of users increases and delivers high performance. Unfortunately, we can’t say anything good about the Western Digital Scorpio WD1200BEVS and Hitachi Travelstar 5K160 HTS541612J9AT00 because their read speed degrades much as the load increases.

It’s somewhat different with multi-threaded writing. The Hitachi Travelstar 5K160 HTS541612J9AT00 is a loser here as its speed lowers much more than that of the other HDDs at higher loads. The write speed of the Western Digital Scorpio WD1200BEVS doesn’t sink that low. The speed of the Samsung SpinPoint M60S HM120JI is even more stable – this HDD is only slower than the Seagate drive here.