Some three months ago we welcomed early hard disk drives based on 500GB platters but now the situation is completely different. 1.5- and 2-terabyte models from Samsung, Seagate and Western Digital are all available for purchase today, even though all of them belong to power-efficient series with reduced spindle rotation speed. At the time of our writing this, Seagate’s Barracuda 7200.12 is the only series that has a spindle speed of 7200rpm and 500GB platters, but its maximum capacity is 1TB. If you want more storage space, you have to put up with the lower spindle speed. Such HDDs can actually make a very good second hard disk for storing data only. You don’t need high performance from such a disk whereas the lower power consumption and heat dissipation would come in handy. This lucky combination of large capacity and low heat dissipation makes these HDDs suitable for modestly loaded file servers and for household electronics (it is always better to have the opportunity to record 2 terabytes of movies instead of 1 terabyte).
If you are only into 7200rpm models and want to have the highest storage capacity possible, you should just wait a little till the 2-terabyte Western Digital Caviar Black and the similar product from Hitachi hit the shops. By the way, Hitachi is the only maker that begins to produce HDDs larger than 1TB from full-speed models. Hitachi doesn’t offer a power-efficient series. So, until we’ve got large and fast HDDs, it is just the proper time to have a comparative test session and see what today’s high-capacity HDDs can offer.
They are actually not so very slow, those modern 5400rpm drives. Of course, they will always be inferior to HDDs with higher spindle rotation speed, but right now they have an advantage in the way of larger-capacity platters. Although these platters do not provide high sequential speeds, the high recording density makes up for the higher seek time. Here’s the clarification: the average seek time is measured for the full capacity of an HDD but it is usually only a tiny portion of the capacity that is being used at the given moment. If data on your hard disk are not too fragmented, all of a specific application’s data will be located within a few cylinders’ space. The width of a cylinder is somewhat smaller with HDDs that have a larger number of platters and a higher track density (as we already know, this is what modern 500GB platters are in comparison with 333GB platters). So, if we compare a 3-platter 1TB and a 3-platter 1.5TB drive, the latter is going to have only two thirds of the physical cylinder width of the former due to the higher track density. And the 25GB or something zone with your OS and frequently used applications on the 1.5TB drive is going to be only two thirds as wide as on the 1TB drive. It means that, if the heads move at the same speed from one cylinder to another, data are accessed faster on 500GB platters.
You are going to see both 1.5TB and 2TB drives in this test session. There are not enough HDD models with a capacity of over 1 terabyte for two reviews. By the way, the cost of storage per gigabyte is considerably higher with the 2TB models. This should be taken into account when you go shopping for your new hard disk.