Currently, 2.5" enterprise drives are leaving their 3.5” competitors behind. They're faster, more flexible, and now they offer comparable capacities (we're up to 1 TB now). In this piece, it's Hitachi versus Seagate battling for high-density supremacy.

SSDs are slowly but surely sending good old magnetic disk drives into retirement...at least when it comes to the workloads that simply cannot get enough performance.

That's certainly the case in the consumer segment, where it is absolutely worthwhile to replace the Windows boot drive with a quick SSD to accelerate the entire system. However, it is not necessarily the best route for enterprise drives.

SSDs Left Out in the Cold?

Finding the right time and place for SSDs is another story altogether in professional storage environments. Although SSDs offer significantly higher I/O performance, other criteria like reliability and system validation also have to be taken into considered. In contrast to hard drives, the reliability of SSDs is less proven, causing IT decision makers to tread lightly before integrating them into mission critical systems.

Moreover, most solid-state drives employ SATA; only a handful of models support the enterprise-class SAS interface (with its dual ports) that ensure optimal protection against a failed HBA. Really, OCZ is the only player making that technology possible right now with its Talos family.

But it is precisely those virtues that our three test candidates use to score their points. Hitachi's Ultrastar C10K600, Seagate's Constellation.2, and Seagate's Savvio 10K.5 all support the established interfaces and configuration paths with their speedy SAS 6 Gb/s ports, and some models even come with Fibre Channel support. Seagate also offers its drives in a self-encrypting model, which runs a 256-bit AES cipher and is marketed to server environments where secure data storage matters most. Our test candidates also perform admirably in terms of reliability: Hitachi and Seagate estimate the MTBF (mean time between failures) for their C10K600 and Savvio 10K.5 at around 2 million hours; this is a high standard even in the enterprise segment.

Good Things Come in Small Packages

We asked enterprise hard drive manufacturers to tell us why 2.5" disks are a good choice in the server segment, and they gave us three reasons. The most obvious has to do with the power consumption of the IT infrastructure. In contrast to 3.5” hard disks, the smaller drives use less power and consequently don't get as warm, therefore requiring less cooling. Because of this form factor, enterprise hard drives require less space in the server cabinet and therefore contribute to improved scalability. The third argument revolves around the capacity of 2.5” drives, which have matched their 3.5” counterparts at the 10 000 and 15 000 RPM spindle speeds. This is demonstrated Seagate's Savvio 10K.5 and Seagate's Constellation.2, which offer 1000 GB and 900 GB of storage, respectively. Our tests show that the 2.5” drives are also equal to many 3.5” drives when it comes to performance.