Detailing the Drive Types
Seagate vs. WD: Battle for the SOHO NAS Crown
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Broadly speaking, hard drives fall into three categories: desktop/consumer, SOHO/SMB/NAS, and enterprise. Nomenclature varies across vendors and product families, but this is the essential breakdown. Within each category, there may be additional sub-categories, such as a segmenting of the NAS category into sub-categories. Seagate encapsulates this well in the following table:
Let's explore a few of these points. Most readers will be familiar with the SATA interface. SATA has been the primary drive interface type for many years throughout the consumer and SMB worlds. Applications that used to demand the added performance and data security of parallel SCSI now reach for Serial-Attached SCSI (SAS), which is electrically compatible with SATA but integrates a different set of more robust, scalable protocols. Consumer and SOHO markets are unlikely to need SAS features, but SAS can offer unique advantages in certain niche applications where speed and data integrity are paramount.
Interestingly, business drives may offer less throughput in some cases than their desktop counterparts. For example, the 4TB Seagate Desktop HDD specifies a 180 MB/s maximum sustained data rate. The 3TB version reaches to 210 MB/s. (This is because the lower Desktop HDD capacities feature a higher rotation rate.) In comparison, the NAS HDD’s 180 MB/s (see page 11 of the manual, not the chart above) may look disappointing. This is where spec sheets can be misleading. Yes, consumer drives may post short-term performance superior to their enterprise-oriented counterparts, but this ignores the typical use cases and duty cycles of the two drive types. Desktop drives are designed for fairly light loads – occasional file accesses, eight hours per day, five days per week. Business drives are meant to be used constantly – all day, every day. Think of the difference between a Chevrolet Silverado pickup and a Cadillac XTS sedan. Both are made by GM but for very different work types. The Cadillac may go faster sometimes, but you sure wouldn’t pick it to pull a half-ton of gravel through the countryside. And if you did try to sustain such a workload indefinitely, guess which vehicle would fail first.
The NAS HDD uses the same RPM spindle speed as the 4TB Desktop HDD, but it is also meant more for heavy duty hauling than occasional sprints down the strip. Part of this is reflected in the NAS HDD’s lower power consumption. Despite saving half a watt in typical operational draw by dropping down the spin speed, the 4TB Desktop HDD still consumes 7.5W compared to the 4TB NAS HDD’s 4.8W. In a single-drive setting, a difference of 2W to 3W likely won’t matter to many users. But step up to four drives or more running 24x7 and the power savings over the course of years starts to become significant. Moreover, drives generally contain firmware with power profiles that reflect the drive’s expected use parameters. Desktop drives are expected to run eight hours per day, five days per week. Business and enterprise drives are presumed to run with heavier loads around the clock, 365 days per year, and their integrated power profiles should reflect this and minimize total energy consumption accordingly.