A Comprehensive HDD Specification Guide

If you are looking to store your digital goodies with the most bang for the buck, then hard disk drives are undoubtedly the way to go. Whether it’s for a NAS, a secondary drive for some less-played games, or any other use where capacity is a priority over speed—there’s no beating the ‘price per gigabyte’ of HDDs. But how do you pick the perfect drive for your use case?

Although almost any modern drive should fit and work fine if there is a free compatible motherboard slot and power connection present (usually SATA, although older systems might have other connectors), there are a few different things to consider when looking to get the perfect drive. In this guide, I will be going over the what and the how of picking out your new drive (or drives!). But first, let’s take a closer look at what HDDs can offer us that an SSD or some other technology can’t, and what drawbacks there might be.

Why an HDD rather than as SSD?

As previously mentioned, HDDs are the most economic option per GB. This is especially compounded when looking to store more than a few terabytes, as SSDs tend to store much less per drive than HDDs at the same price.

Most SSD options commonly for sale max out at 8TB at the time of writing this, while HDDs can easily be found for 12, 14, 16, and even 18TB—and 8TB HDD options are usually half or even a quarter of the cost of their SSD counterparts. Just don’t expect the same access times, as even the cheapest SSDs beat HDDs by a reasonable margin. (For a specific breakdown of the speed differences we’re talking about, take a look at this article on data transfer rates and this article on SSDs.) Speed-conscious and noise-conscious users should keep an eye out further below, though, as I’ll be covering some in-between alternatives so those who want the best of both worlds.

You might be wondering which is better as a long-term storage solution. Well, longevity has been largely evened out between both types of drives. SSDs initially had a bad reputation for dying after a relatively low number of read and write operations, but the technology has come a long way in the last decade. HDDs still experience the same wear over time as they always have, though, due to their plethora of moving parts (which can be damaged through excessive vibrations and impacts).

2.5-inch or 3.5-inch?

The first specification we’ll consider is what physical size you need. Generally, smaller-sized 2.5-inch drives are the only drives you’ll be able to fit in a laptop, while 3.5-inch drives are what you’ll typically get in a desktop or server. 3.5-inch drives take a bit more power to operate, but they come in much larger capacities and are much more common. Still, there is no particular reason you couldn’t install a 2.5-inch drive into a desktop system, if you are particularly low on space within your case, or are even building in a small form factor case.

2.5 inches is also the only size that consoles like the PS4 support. But with smaller physical sizes come smaller capacities. The current max size available on a 2.5″ HDD is 2TB, so these drives are only really a good buy when looking for a single small-capacity drive. A good 2.5″ option to consider is the Black Series of drives from Western Digital such as this 1TB 7200rpm one.

Consumer or Enterprise?

Another thing to decide on would be whether you are looking for a standard consumer drive or a more Server / Enterprise oriented drive. The latter, as is evident in the name, are built with a server environment in mind. This means greater reliability, resilience to vibrations from lots of neighboring drives, sometimes greater speeds, different firmware (more on that down below) and longer warranties. But they also carry a larger price tag per GB.

Really, the choice here comes down to what you are looking to do with your drive. If you need to have your drive working 24/7 moving tons of data around, or are stacking drives up in a confined space, then an enterprise drive is the way to go. Otherwise, a consumer drive should be the go-to. There are loads of options for both types of drive, though, with many consumer manufacturers also offering Enterprise lineups (with some drives even being specialized for specific workflows). Some good enterprise drives to consider would be the 16TB 7200rpm WD Red Pro or the SeaGate IronWolf NAS 6TB 5600rpm.

RPM, Cache, and Speed

The next (arguably most important) thing for most to consider, would be the speed of the drive. Measured in RPM (rotations per minute), some common speeds are 5400, 7200, or even 10k for certain rare enterprise options. A good speed that is widely available from most manufacturers is 7200rpm—pretty solid for most uses, providing a good balance between speed of access and price.

As for 10k rpm and above drives, these are now mostly out of production for regular consumers and will probably be not easy to find. The segment of the market interested in such high-speed drives has migrated almost entirely to SSDs. Moreover, 10k drives are louder, produce more heat, break more easily, and come in lower capacities. For more information, including benchmarks, storagereview has an in-depth review from 2012 on the 1TB WD VelociRaptor; it’s a good option that is miraculously still available to buy. Although antiquated, a 10k drive might still be a good choice if you can manage to get one for much cheaper than a modern equivalent-capacity SSD (which are all much faster, quieter, and more reliable in almost all situations).

Speaking of speed, another factor to consider that will affect the performance of your drives is the cache. This is a small amount of high-speed storage that speeds up access times to the drive by temporarily stowing some data. Caches can come in many different sizes, with some drives reaching up to 512MB (and SSD caches go even higher).  Most drives of a certain capacity will have similar amounts of cache, but sometimes it might be possible to find some drives with more, such as the Seagate Barracuda Pro Compute 1TB 7200rpm which comes with 128 MB of cache instead of the 64mb or 32mb most other drives of this capacity have.

Larger-capacity drives have larger caches, but budget versions might come with less. In essence, the more cache you can get, the better.

Technology and Firmware

One important specification that might not always be so obvious (but very important when looking for drives with a specific use case) is the way drives are built, per se. SMR and CMR/PMR are two different types that you could see if you take a closer look at the drive model datasheet that manufacturers provide on their websites.

SMR (Shingled Magnetic Recording) drives write data in a specific way where data is written on top of adjacent data, roughly speaking. This means that writing operations compared to reading are much slower on these kinds of drives, because of extra time spent rewriting overwritten data. But this doesn’t mean that SMR technology drives should be totally avoided. In fact, you might be able to save a buck if you know that you won’t be writing to your drives as much as reading from them (using drives for archiving, etc.).

CMR (Conventional Magnetic Recording) drives, also known as PMR (Perpendicular Magnetic Recording) drives, on the other hand, write data without this kind of overwrite and allows data to be stored in greater density—closer together on the physical platter(s) of the drive. This means that drives with this technology will tend to be much faster when used for more data write or transfer-intensive purposes (This includes NAS servers and general secondary drive usage). But keep in mind that this performance doesn’t come for free. PMR/CMR drives will be more expensive than their SMR counterparts.

Another specification to look out for is firmware; this is the software that controls how the hard drive operates, and can be optimized for specific use cases such as surveillance (like the Seagate SkyHawk 8TB 7200rpm). Look for what the manufacturer specifies the drive is for, if anything, as firmware can play a big role in how fast and how long your drive will perform.

Hybrid Drives: Are They Worth It?

One type of drive that can act as a compromise between an SSD and an HDD is an SSHD. This is an HDD with a small amount of NAND Flash (SSD Storage Technology) onboard. Special controllers and firmware automatically optimize which of your data should go on the faster storage, and which should go on the slower disk according to access frequency. This allows the drive to be a little bit faster than its traditional counterparts, even if the NAND storage is usually limited in size (around 32GB max).

If you’re looking to give your drives a bit more apparent speed, then a hybrid might be a pretty good in-between option. There aren’t really many models, though, as these drives tend to be somewhat niche, in a sort of ‘no mans land’ between SSDs and HDDS (much like the 10k RPM drives). The SeaGate FireCuda 1TB 5400rpm with 8gb is a decent pick, just keep in mind that this (and all hybrid drives) are only really worth it if you are planning on accessing the same data many times (e.g. playing an RPG that you are planning to sink many hours into). Otherwise, look for the wider selection of regular drives that will probably end up being much cheaper… and possibly still faster.

Closing Remarks

Hopefully, you should have some idea of what to look for when picking out a drive now; any well-known brand should be fine, if the warranty and specifications fit your needs. Make sure to take a look at individual reviews for any drive you pick, and you should have no issues finding the perfect drive!

What do you think is the most important specification for a drive? Would you prefer to go the hard disk route, or spend more on an SSD solution? Let us know in the comments!