Buying A New Hard Drive: 7 Things You Must Know

All hard drives die. It’s normal to purchase a new one every few years, either to replace an old hard drive or to use as additional backup drives.

But which hard drive should you buy? What hard drive do I need?!

Hard drive shopping doesn’t have to be difficult. In fact, there’s a lot of room for error, so don’t be anxious! Just follow these guidelines and you won’t have to worry about buying the wrong hard drive.

1. Hard Disk Drive vs. Solid State Drive

The first consideration when deciding to buy a data storage drive is whether you need a solid state drive (SSD). While SSDs serve the same general function as traditional hard disk drives (HDDs), they have a few pros and cons.

An SSD is a type of data drive that uses flash memory instead of the spinning metal disks found in traditional HDDs. Think of an SSD like a massive USB drive or SD card.

But how important is that distinction?

SSDs read and write data faster.

SSDs draw less power, which conserves energy and extends laptop battery life.

SSDs have no moving parts so they make no noise and have longer lifespans.

SSDs are more expensive per gigabyte, meaning they have smaller data capacities than HDDs at any given price point.

If money is a limiting factor and you need as much storage space as you can get, go with a traditional HDD. If you’re buying the drive mainly for data backups and long-term data storage, go with a traditional HDD.

Seagate BarraCuda 4TB 3.5-inch Internal HDDSeagate BarraCuda 4TB 3.5-inch Internal HDD

If the drive is going to run an operating system or hold a lot of frequently accessed files and programs, then go with an SSD instead. Speed and performance are the primary benefits of an SSD over an HDD.

Samsung 860 EVO 1TB 2.5-inch Internal SSDSamsung 860 EVO 1TB 2.5-inch Internal SSD

2. Hard Drive Sizes and Interfaces

Once you’ve decided between HDD and SSD, you have to pick a form factor. Thankfully, there are only two “real” choices and the right choice is mostly dictated by your current setup.

Data drives come in two form factors: the 3.5-inch drive and the 2.5-inch drive.

In HDDs, data is stored on spinning metal disks, which means that more disks are needed for greater data capacity. For this reason, desktop HDDs tend to be 3.5-inches with a maximum capacity of 12TB while laptop HDDs tend to be 2.5-inches with a maximum capacity of 5TB (as of this writing).

Image Credit: Matee Nuserm/Shutterstock

SSDs don’t have any moving parts, so they can be made smaller than HDDs. As such, most SSDs come in the 2.5-inch form factor. What if you need to fit an SSD into a 3.5-inch enclosure? There are adapters that let you turn 2.5-inch drives into 3.5-inch drives.

As for connections, most modern internal drives (both HDD and SSD) use SATA connectors. Older internal HDDs that were manufactured before the SATA standard use IDE connectors instead. External drives, however, connect to your system through USB ports regardless of whether they’re HDDs or SSDs.

Note: Not sure what SATA, IDE, or USB mean? Check out our post on common computer cables.

3. Hard Drive Specifications and Performance

Here’s what to look for in a modern hard drive:

Storage capacity. HDDs come in a wide range of capacities, capping out at 16TB per drive due to physical limitations. SSDs can’t hold as much space, and consumer-grade SSDs currently max out around 5TB per drive.

Transfer speeds. The performance of a consumer-grade HDD is determined by many factors, but revolutions per minute (RPMs) is an important one. Higher RPMs means faster transferring of data to and from the drive.

You can ignore the drive’s SATA speed. For example, a modern drive might be listed as 3.0GB/s and 7200RPM. That first value is the SATA speed, which describes the theoretical maximum speed of a SATA connection. No HDD can transfer data at that kind of speed. However, a 7200RPM drive will always be faster than a 5400RPM drive.

Cache space. When a hard disk needs to transfer data from one section of the drive to another, it utilizes a special area of embedded memory called the cache (or buffer).

A larger cache enables the data to transfer faster because more information can be stored at one time. Modern HDDs can have cache sizes ranging from 8MB to 256MB.

Access times. Traditional HDDs have a couple of other factors that impact performance, such as the time it takes for the reader to position itself to read data from or write data to the drive.

While it’s true that two 7200RPM drives could perform differently (e.g. one of them might be slower at re-positioning the disk reader), there’s no standard way to compare access times. Plus, most hard drives perform at similar levels these days, so don’t worry too much about this particular detail.

For SSDs, you’ll want to look for sequential read and write speeds (also called sustained read and write speeds). As long as those speeds are within the SATA connector’s max speed, which they most likely will be, you should be fine.

Failure rate. Since HDDs have moving parts, wear and tear is expected over time—but not all HDDs wear at the same rate. Some models are prone to fail within 12 months while others have average lifespans exceeding six years. It’s your responsibility to research this on a per-model basis prior to making a purchase.

On the whole, according to StorageReview, modern SDDs tend to last longer (average failure rate of 2.0 million hours) than modern HDDs (average failure rate of 1.5 million hours). However, for long-term storage of data that stays disconnected for months or years, HDDs are more durable than SSDs.

4. Price and Cost of Hard Drives

When shopping, you’ll run into a wide range of hard drive prices for devices that all look very similar on the surface. It’s up to you to decide which factors and features are most relevant to your needs, then select a hard drive that fits those needs.

However, one way to determine value is to divide the drive’s price by its storage capacity to get its price-per-gigabyte.

For example, consider the WD Black HDD series.

The WD Black 1TB Internal HDD is an all-around great purchase for everyday consumers at $0.07 per GB. Note how doubling the storage capacity with the WD Black 2TB Internal HDD costs less than twice the price at $0.05 per GB. And if you double it again with the WD Black 4TB Internal HDD, it’s even more affordable at $0.04 per GB. The trend holds true for the WD Black 6TB Internal HDD at $0.03 per GB.

WD Black 6TB Internal HDDWD Black 6TB Internal HDD

May also be available from: Newegg ($99.82).

Which one of these offers the best value? The 6TB model. The 1TB, 2TB, 4TB, and 6TB models have price-per-gigabyte values that decrease with larger storage space. There are other drives that DON’T become more affordable with scale though, so you have to be careful: some drives cost more per-gigabyte at higher capacities.

For example: The Samsung 860 EVO 250GB Internal SSD is affordable, and the Samsung 860 EVO 500GB Internal SSD grants twice the space for less than twice the price, and when you get up to the Samsung 860 EVO 1TB Internal SSD, you get the best bang for your buck. But the Samsung 860 EVO 2TB Internal SSD costs way more than twice the price of the 1TB!

Samsung 860 EVO 1TB Internal SSDSamsung 860 EVO 1TB Internal SSD

5. External Hard Drives vs. Internal Hard Drives

The final thing to consider is whether this hard drive is going to housed in a desktop case/laptop body or used externally to connect to many different devices.

External drives are ideal for storage, backups, and transfers. They typically connect using USB 2.0, 3.0, or 3.1, which have maximum transfer speeds of 60MB/s, 625MB/s, and 1,250MB/s, respectively. USB 3.1 is preferable of course, but not essential unless you’re transferring hours of data back and forth every single day.

External drives are portable. They can be shared between multiple computers without any hassle. Just unplug the USB, plug it elsewhere, and you’re done. They can also be plugged into TVs and media centers for direct media playback.

In all other cases, internal drives are preferable.

Note: Any data drive can be used internally or externally—external drives are essentially internal drives that are placed in a special protective casing. If you buy an external drive, you can actually take it out of the casing and use it internally!

How to Choose an External Hard Drive

For external drives that are mainly used for transferring files back and forth, get an SSD with USB 3.1 support for speed and performance. We really like the Samsung T5 500GB USB 3.1 Portable SSD and have had much success with it.

Samsung T5 500GB USB 3.1 Portable SSDSamsung T5 500GB USB 3.1 Portable SSD BUY NOW ON AMAZON

May also be available from: B&H ($89.99); Dell ($89.99); Newegg ($89.99); Samsung($99.99).

For external drives that are mainly used for long-term data storage, get a large HDD like the affordable WD Elements 4TB Portable External HDD. I use this for personal storage myself, and I won’t be running out of space any time soon!

WD Elements 4TB Portable External HDDWD Elements 4TB Portable External HDD

If data security is your primary concern, you might consider something like the Transcend 2TB StoreJet M3 External HDD. It comes with military-grade shock resistance, an anti-shock rubber case, an internal suspension system that can survive drops, and built-in 256-bit AES encryption.

6. Gaming Hard Drives: PlayStation, Xbox, PC

Your hard drive choice can significantly impact the performance of games, which is why we always recommend SSDs for gaming. This is true for PCs, Xbox One, Xbox One X, PlayStation 3, PlayStation 4, PlayStation 4 Slim, PlayStation 4 Pro, or any newer gaming console.

Since SSD speeds far exceed HDD speeds, games will launch much faster and load much faster between levels, stages, and maps. Seriously, the difference between SSDs and HDDs for gaming is night and day. You’ll regret getting an HDD!

When choosing a drive, you have to stick to the parameters of the device:

  • For PCs: Any hard drive will work as long as you know the form factor of the hard drive bays in your case and the connection types on your motherboard. Again, it’s most likely 3.5-inch for desktops and 2.5-inch for laptops and most likely SATA connections.
  • For Xbox 360: The original Xbox 360 uses 2.5-inch hard drives set within custom cases. To upgrade or replace, you’ll need to buy one of Microsoft’s overpriced replacements. Third-party drives can be used but need to be applied with Xbox-compatible firmware, which is far beyond the scope of this article.
  • For Xbox 360 S and E: The hard drives used in Xbox 360 S and E consoles are incompatible with the original Xbox 360, and vice versa. The 4GB models have internal flash memory that can’t be removed or replaced. The 250GB models can be upgraded to 500GB by purchasing one of Microsoft’s overpriced replacements.
  • For Xbox One: The Xbox One supports external drives through USB 3.0, which means you can use pretty much any SSD. Unfortunately, there’s no easy way to replace the internal drive. Learn more in our article on taking advantage of Xbox One external drives.
  • For Xbox One X: The Xbox One X also supports external drives through USB 3.0 with a minimum size of 256GB. Unfortunately, there’s no easy way to replace the internal drive, and doing so will void your warranty.
  • For PlayStation 3: All PlayStation 3 models have 2.5-inch SATA drives that can be replaced and upgraded by users without hassle.
  • For PlayStation 4: All PlayStation 4 models, including Slim and Pro, have 2.5-inch SATA drives that can be replaced and upgraded by users without hassle. They also support external hard drives through USB 3.0.

7. Internal and External Hard Drives for Mac

If you’re on a MacBook Air, MacBook Pro, Mac Mini, or iMac, then there are a handful of extra considerations you should keep in mind when buying a hard drive.

Internal Mac Hard Drives

The most important thing is that Mac hard drive upgrades are pretty much DIY projects. You have to tear your device apart just to reach the internal drive, carefully replace it, and then put everything back together. Even the easiest replacement can take at least an hour. This also voids your warranty and any AppleCare insurance you might have.

All MacBook Air, MacBook Pro, Mac Mini, and iMac models 2012 and later use an internal 2.5-inch form factor (except for 27-inch iMacs, which use an internal 3.5-inch form factor). Fortunately, 3.5-to-2.5-inch adapters do exist.

Things get a bit murky as far as SATA, PCIe, NVMe, and AHCI are concerned. For example, 21.5-inch iMacs in 2017 only have a PCIe slot if the device was initially fitted with a Fusion Drive. You won’t know which connections are available in your exact device unless you specifically look it up.

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