Hard drives may not always get a lot of respect in the computer industry, but few other products have experienced more exciting price-performance movement across their lifetimes. Hard drives capable of carrying multiple terabytes of data are becoming increasingly common in mainstream machines, and with 6-Gbps SATA connections able to transfer that data quickly. So 2TB drives, like Seagate's new Barracuda Green ($279.99 list), can be good solutions for getting your storage needs under control. This drive also uses less power, thus earning its "green" moniker, which means it spins more slowly—and costs more—than most desktop 3.5-inch hard drives. But if you are willing to put up with that and only need wide vistas of empty space for photos, video, and the like, this Barracuda isn't a bad drive to hook.

The Barracuda Green's biggest sticking point is, in fact, that rotational speed: 5,900 rpm, well below the 7,200 rpm that has long been the standard for desktop-size hard drives, but above the 5,400 rpm we usually see for low-power drives. The drive's 6-Gbps SATA transfer capabilities and 64MB of cache will help a little, but there's no getting around the fact that you won't want to use the Barracuda Green as a boot drive. For that purpose, stick with a 7,200-rpm (or, even better, a 10,000-rpm) hard drive, or even a solid-state drive (SSD), and leave this one hooked up to give yourself plenty of extra space without needing to worry about exactly how fast stuff moves onto or off of it.

Still, you should know what you're getting. So we subjected the 2TB Barracuda Green and a 2TB Western Digital Caviar Green (which, for the record, does not support 6-Gbps SATA) to our battery of storage benchmarks to see how these two low-power drives compared. We also ran the same tests on a more mainstream drive, the 7,200-rpm WD Caviar Black, for purposes of comparison.

Performance
In most of the most important tests, the Barracuda Green was faster than the Caviar Green. In HD Tune Pro, it averaged higher read (107.9 MBps versus 95.2 MBps) and write (98 MBps versus 93 MBps); we saw similar results in the HDTach long benchmark, where the Barracuda pulled out 112.8 MBps versus 100.2 MBps. The results continued along these lines in CrystalDiskMark, with the Barracuda Green decisively winning every challenge except the 512-byte write and 4KB QD32 write tests, where the Caviar Green pulled just ahead (with 73 MBps versus 69 MBps and 1.2 MBps versus 1 MBps respectively). In the AIDA64 disk benchmark read tests, the Barracuda Green triumphed across the board; the Barracuda Green's numbers were also higher in the PCMark Vantage hard drive test (4,660 versus 3,868) and the SiSoftware Sandra read test (108.43 MBps versus 96.85 MBps).

The Caviar Green did, however, win consistently in the areas of disk access time and burst rate—despite having a slower rotational speed. Its access times were a shade better in HD Tune (15.1 ms versus 16.6 ms), HDTach (15 ms versus 16.6 ms), AIDA64 (14.7 ms versus 16.77 ms), and SiSoftware Sandra (10.8 ms versus 16.86 ms). Its superior burst capabilities showed when writing in HD Tune (194.1 MBps versus 159 MBps) and in HDTach (240.8 MBps versus 208.7 MBps); when writing in HD Tune, the Barracuda Green had the edge (212.6 MBps over 194.7 MBps). Burst rate, the highest possible rate at which data can be transferred from the drive interface to the OS, doesn't have a strong impact on everyday usage, but the slightly improved access times may help to marginally mitigate the difference between the drives' rotational speeds.

We should point out, however, that the faster Caviar Black was the overall champ—despite costing quite a bit less (as of this writing, a 6-Gbps version of it can be found on NewEgg.com for $170). It didn't ace absolutely every test, but it came in first in most of them, with read speeds that generally trounced the competition. Some representative scores: average HD Tune write and read times of 114 and 115 MBps; an HDTach read time of 120.5 MBps; 2.19 MBps and 2.259 MBps in CrystalDiskMark's 4KB and 4KB QD32 write tests—twice the other drives' scores; a 6,404 in PCMark Vantage; and the lowest overall access times (11.5-11.6 ms in HD Tune, HDTach, and AIDA64, and 5 ms in SiSoftware Sandra).

The important question with regards to the 2TB Seagate Barracuda Green, then, is how much speed really means to you. In most cases we'd recommend going with a faster (and less-expensive) 7,200-rpm drive like the Caviar Black (or Seagate's own Barracuda XT, which costs the same), just to save money. But if maximizing your electricity usage—and thus your power bill—is a prime concern, the Barracuda Green's 6-Gbps SATA capability and faster-than-usual rotational speed are attractive features. If you'd prefer to go green rather than save green, it's as good a choice in that realm as you can currently find.

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