SAS Storage: High-Performance Hard Drives

Test Setup and Transfer Diagrams

The Ultrastar 15K450 has an impressive transfer diagram, as the drive manages to maintain a very high throughput of almost 150 MB/s over almost half of the drive’s surface. This means that the drive is capable of reading or writing at 140 MB/s as long as you do not utilize more than 200 GB of capacity. Even if you start utilizing more capacity, the transfer rates typically do not drop much below 100 MB/s, which is an excellent result. Most flash based SSDs can reach that, but they don’t provide the maximum of almost 160 MB/s.

Seagate’s Cheetah 15K.6 transfer diagram is more conventional. The drive delivers almost 175 MB/s at the beginning of the medium, and goes down to still over 100 MB/s when you utilize the entire 450 GB. While there are more steps than in Hitachi’s Ultrastar 15K450 diagram, the Seagate drive still manages to provide better throughput than the Hitachi drive in all areas of the medium. This is the fastest mechanical drive we’ve had in our test lab—it’s definitely well faster than flash SSDs when it comes to sequential throughput. Congratulations to Seagate.