We'll kick things off with HD Tune, our synthetic benchmark of choice. Although not necessarily representative of real-world workloads, HD Tune's targeted tests give us a glimpse of a drive's raw capabilities. From there, we can explore whether the drives live up to their potential.
The second line graph is the same as the first, but the SSDs have been removed for a better look at the mechanical terabyte drives. Among them, Samsung's Spinpoint F3 manages the highest read speeds across its entire capacity. The drive's transfer rate oscillates quite a bit more than that of the others, but even in the deepest valleys, the Spinpoint is still a step ahead of its closest competition, the Deskstar 7K1000.C.
Slightly trailing the Samsung and Hitachi drives are entries from Seagate and WD. Looking at average read rates, the Barracuda and Caviar are 11 and 14MB/s slower than the Spinpoint, respectively. That's a particularly poor start for the Caviar, whose high areal density should give it an advantage with sequential transfers.
Switching gears from reading to writing doesn't change the picture much for our mechanical terabyte drives. The Spinpoint still leads the Deskstar, albeit by a slightly smaller margin, while the Caviar and 'cuda remain in third and fourth place, respectively.
As we saw with reads, the Deskstar is the only drive to maintain a smooth transfer rate curve over the extent of its capacity. The Spinpoint's write speed bounces around seemingly at random, although thankfully without much amplitude. Meanwhile, the Caviar and Barracuda see their write speeds drop in small steps at several points across their respective capacities.
Next up: some burst-rate tests that should test the cache speed of each drive. We've omitted the X25-V RAID array from the following results because it uses a slice of system memory as a drive cache.
Notch two wins for the Barracuda 7200.12. Seagate tops our collection of terabyte mechanical drives with a 206MB/s burst speed for both reads and writes. The Spinpoint is more than 10MB/s off the pace, followed by the Caviar and Deskstar.