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Hard drives are a key component in modern computers. It’s normal to purchase a new one every few years, either to replace an old hard drive or to use as an additional hard drive.

But with so many choices out there, which one is best for you? Which one should you buy?

The good news is that hard drive shopping isn’t all that difficult. In fact, there’s a lot of leeway for error here — as long as you follow these guidelines, you won’t have to worry about “buying the wrong hard drive” or anything like that.

Hard Disk Drive vs. Solid State Drive

The absolute first decision to make as far as data storage is concerned is whether or not you want a solid state drive (SSD). While an SSD fulfills the same function as a traditional hard disk drive (HDD), it has its own set of pros and cons.

For those who don’t know, an SSD is a type of drive that uses something called flash memory for storing data instead the spinning metal disks you’d find in a traditional HDD. Think of it like a massive USB thumb drive.

What difference does it make, anyway?

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hard-drive-guide-hdd-vs-ssd
Image Credit: Hadrian via Shutterstock

First, SSDs are faster at reading and writing data. Second, SSDs require less power draw which conserves energy and extends laptop battery life. Third, SSDs have no moving parts so they make no noise and have longer lifespans. The downside is that SSDs are more expensive and have smaller data capacities than HDDs.

What’s the bottom line? If price is a big concern, go with a traditional HDD. Or if you’re buying the drive mainly as a backup drive, go with a traditional HDD. And as far as HDDs are concerned, you can’t go wrong with the WD Blue 1 TB HDD which only costs $50.

WD Blue 1TB SATA 6 Gb/s 7200 RPM 64MB Cache 3.5 Inch Desktop Hard Drive (WD10EZEX) WD Blue 1TB SATA 6 Gb/s 7200 RPM 64MB Cache 3.5 Inch Desktop Hard Drive (WD10EZEX) IntelliSeek: Calculates optimum seek speeds to lower power consumption, noise and vibration. Buy Now At Amazon $49.74

But if the drive is going to run an operating system or hold a lot of frequently-accessed files and programs, especially video games, then go with an SSD instead. And as far as SSDs are concerned, you can’t go wrong with the Samsung 850 EVO 500 GB SSD which costs about $160 but performs well and lasts a long time.

Samsung 850 EVO 500GB 2.5-Inch SATA III Internal SSD (MZ-75E500B/AM) Samsung 850 EVO 500GB 2.5-Inch SATA III Internal SSD (MZ-75E500B/AM) Powered by Samsung V-NAND Technology; Optimized Performance for Everyday Computing. Buy Now At Amazon $160.00

Physical Size and Interface

Once you’ve decided between an HDD and SSD, you have to pick a form factor. Thankfully, there are only two choices and the right choice will mostly be dictated by your current setup. Don’t worry, this decision will be easy.

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

hard-drive-guide-form-factor
Image Credit: Matee Nuserm via Shutterstock

In traditional HDDs, data is stored on spinning metal disks, which means that more disks are needed for expanded data capacity. For this reason, desktop HDDs tend to be 3.5-inches with a maximum capacity of 4TB while laptop HDDs tend to be 2.5-inches with a max capacity of 2TB.

On the other hand, SSDs can be made smaller because they don’t require movable parts. As such, most SSDs fit the 2.5-inch form factor. However, if you need to fit an SSD into a 3.5-inch connector, there are adapters available.

As far as connections are concerned, most modern consumer drives — both HDD and SSD — use SATA connectors. Older HDDs that were created before the SATA standard will likely use IDE connectors instead. And if you’re buying an external drive, it will connect to your system through a USB port.

Note: Not sure what SATA, IDE, or USB mean? Check out our post on common computer cables What Are The Different Computer Cable Types You Should Know As A User? What Are The Different Computer Cable Types You Should Know As A User? Take a look at any piece of equipment related to computer harder and you’ll soon find yourself in a swirling maelstrom of acronyms and foreign jargon. What does it matter if you use IDE or... Read More to get up to speed.

Specifications and Performance

Now that you know what kind of drive to buy, it’s time to find the best one that fits your needs. Here’s what you need to consider.

Storage capacity. HDDs come in all sizes, capping out at 4TB per drive due to physical limitations. On the other hand, SSDs are much smaller and haven’t yet been able to break the 1TB mark. Even so, consumer-level SSDs rarely exceed 512GB.

Transfer speeds. The performance of a consumer-level 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.

Also, ignore the drive’s SATA speed. For example, a modern drive might be listed as 3.0 GB/s and 7200 RPM. No HDD is ever going to be able to transfer data at speeds of 3.0 GB/s, but a 7200 RPM drive will always be faster than a 5400 RPM drive.

hard-drive-guide-cache-space
Image Credit: Nata-Lia via Shutterstock

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.

Larger cache will enable the data to be transferred faster (because more information can be stored at one time). Modern HDDs can have cache sizes ranging from 8 MB to 128 MB.

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 7200 RPM drives could have differing performances — e.g. one of them might be slower at repositioning the reader — there’s no standard way to compare access times. Plus, most hard drives perform at similar levels these days, so I wouldn’t worry too much about this particular detail.

hard-drive-guide-ssd-diagram
Image Credit: Zern Liew via Shutterstock

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 are mechanical, wear and tear is expected over time; that being said, not all HDDs are made equal. Some models are prone to fail within 6 months while others have average lifespans that exceed 6 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 disconnected storage, HDDs are far more reliable than SSDs.

Are you worried about hard drive failure? Consider setting up RAID storage What Is RAID Storage & Can I Use It On My Home PC? [Technology Explained] What Is RAID Storage & Can I Use It On My Home PC? [Technology Explained] RAID is an acronym for Redundant Array of Independent Disks, and it’s a core feature of server hardware that ensures data integrity. It’s also just a fancy word for two or more hard disks connected... Read More to keep your data protected against sudden and unforeseen malfunctions.

Pricing

Based on all of the above, you’re going to run into a wide range of prices for hard drives that look very similar on the surface. It’s up to you to decide which factors are most relevant to your needs and to select a hard drive that fits those parameters. To determine value for money, divide the drive’s retail price by its storage to get a price per gigabyte.

For example, the WD Black 1 TB HDD ($70, $0.07/GB) is an all-around good purchase for the everyday consumer. However, bumping up the storage capacity to the WD Black 2 TB HDD ($125, $0.06/GB) will nearly double the price. Bumping up the capacity again for the WD Black 4 TB HDD ($235, $0.05/GB) will cost you a pretty penny. Although it’s hard to swallow, the 4 TB drive offers the best value for money.

Western Digital 4TB 7200 RPM SATA 6 Gb/s 64MB Cache, 3.5-Inch Desktop Hard Disk Drive (WD4003FZEX) Western Digital 4TB 7200 RPM SATA 6 Gb/s 64MB Cache, 3.5-Inch Desktop Hard Disk Drive (WD4003FZEX) Next-generation desktop performance hard drive designed to intensify your PC experience Buy Now At Amazon $225.00

The trend is mirrored for solid state drives. The Samsung 850 EVO 250 GB SSD ($95, $0.38/GB) is affordable, but the Samsung 850 EVO 500 GB SSD ($157, $0.31/GB) grants twice the space for less than twice the price. And when you get up to the Samsung 850 EVO 1 TB SSD ($305, $0.30/GB) your wallet will start to sweat, but it offers the best bang for your buck.

Samsung 850 EVO 1TB 2.5-Inch SATA III Internal SSD (MZ-75E1T0B/AM) Samsung 850 EVO 1TB 2.5-Inch SATA III Internal SSD (MZ-75E1T0B/AM) Powered by Samsung V-NAND Technology; Optimized Performance for Everyday Computing. Buy Now At Amazon $309.99

And as you can tell, the HDDs offer a whole lot more space than the SSDs even though they progress at similar price points.

External vs. Internal

The final thing to consider is whether this hard drive is going to housed within the casing, or used externally. It’s an easy decision, but let’s take a look at the pros and cons of each.

External drives are perfect for storage and backups. They typically connect using a USB 2.0 cable which caps out at 480 Mb/s, though later models may support USB 3.0 which caps out at 5.0 Gb/s. Unless you can get one of the latter, the speed will likely be too slow for primary use (e.g. running an operating system).

hard-drive-guide-external-hdd
Image Credit: BLACKDAY via Shutterstock

The trade-off is that 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.

If you need the speed, don’t need the portability, or if your system lacks a working data drive (e.g. if your last one malfunctioned and you need to replace it), then use it internally.

To clarify, any data drive can be used internally or externally as long as the connectors are compatible. When used externally, drives are simply encased in protective casings. If you bought an external drive, you can remove the actual drive and use it internally if you desire.

We recommend using HDDs for external drives because you rarely need the performance of an SSD for that, plus HDDs tend to hold up better over time. Just make sure you get one with USB 3.0 support, like the Seagate Expansion 1 TB Portable HDD which is very affordable at $55.

Seagate Expansion 1TB Portable External Hard Drive USB 3.0 (STEA1000400) Seagate Expansion 1TB Portable External Hard Drive USB 3.0 (STEA1000400) System requirements : Windows 8, Windows 7 Operating System Buy Now At Amazon $54.99

If you’re looking to maximize absolute capacity, then opt for the non-portable version called the Seagate Expansion 8 TB Desktop HDD which is pretty hefty at $230. However, you do get 8 TB of storage space, and if you think of that in TBs-per-dollar, it’s one of the best deals you’ll ever find.

Seagate Expansion 8TB Desktop External Hard Drive USB 3.0 (STEB8000100) Seagate Expansion 8TB Desktop External Hard Drive USB 3.0 (STEB8000100) Easy and simple to use - simply plug in the power adapter and USB cable Buy Now At Amazon $204.95

But if data security is your primary concern, you may want to go with the Transcend 1 TB StoreJet M3 HDD which is competitively priced at $57. What’s so good about it? It comes with military-grade shock resistance, has an anti-shock rubber case, an internal suspension system that can survive drops, and built-in 256-bit AES encryption.

Transcend 1 TB StoreJet M3 Military Drop Tested USB 3.0 External Hard Drive (TS1TSJ25M3) Transcend 1 TB StoreJet M3 Military Drop Tested USB 3.0 External Hard Drive (TS1TSJ25M3) Military-grade shock resistance, SuperSpeed USB 3.0 compliant and backwards compatible with USB 2.0 Buy Now At Amazon $54.99

All that being said, if speed is of utmost importance and you don’t have that much data to store, then an external SSD might actually be preferable. These are rarer than external HDDs so pickings are slimmer, but good options exist — like the Samsung T3 500 GB Portable SSD which costs $170. Just make sure to use a USB 3.1 cable otherwise you won’t get the full transfer speed.

Samsung T3 Portable SSD - 500GB - USB 3.1 External SSD (MU-PT500B/AM) Samsung T3 Portable SSD - 500GB - USB 3.1 External SSD (MU-PT500B/AM) Portable Design with Internal SSD-level Performance Buy Now At Amazon $177.99

Wrapping It All Up

Now you know all there is to know about buying a new hard drive. Once purchased, be sure to take care of your hard drive How to Care for Your Hard Drives and Make Them Last Longer How to Care for Your Hard Drives and Make Them Last Longer Sometimes an early death is the fault of the manufacturer, but more often than not, hard drives fail earlier than they should because we don't take care of them. Read More properly in order to extend its lifespan and keep it clean with these hard drive organization tips Go Clean Your Hard Drive: 5 Things You Can Do in 10 Minutes or Less Go Clean Your Hard Drive: 5 Things You Can Do in 10 Minutes or Less Cleaning your hard drive is about as much fun as it sounds, but what if you could make a real difference in as little as ten minutes? Read More .

Do you have any spare hard drives lying around? Don’t throw them away! Here are some neat ways to breathe new life into old hard drives 3 Ways To Breathe New Life Into An Old Hard Drive 3 Ways To Breathe New Life Into An Old Hard Drive It's in the human nature to collect stuff and in the digital age we mostly collect data. For a long time, the storage capacities of hard drives seemed to increase too slow to match user... Read More . Wring some more value out of them!

Have any questions? Got any other hard drive buying tips to throw into the mix? Share your thoughts with us in the comments below!

Image Credits: Portable Drive Stack Via Shutterstock, SSD vs. HDD Via Shutterstock, Form Factor Comparison Via Shutterstock, Open Hard Drive Via Shutterstock, SSD Diagram Via Shutterstock, External Hard Drive Via Shutterstock

  1. Phillip
    November 23, 2016 at 3:58 am

    If like to leave a note about any drive being usable internally, I bought an external WD drive 3 years ago that had a USB 3.0 interface directly on the drive instead of having a SATA to USB adaptor in the case

  2. amita s
    August 30, 2016 at 9:31 am

    AMAZING ARTICLE!

  3. Harsha
    August 23, 2016 at 6:40 am

    This was detailed post, but I think storing data on personal computer is safe when compared to laptops, but unfortunately we tend to lose data when hard disk crashes due to technical failures in my case it was no UPS, so I thought I should give heads up and have similar article in my blog newandroidphones.in

  4. Rishu
    August 21, 2016 at 8:54 pm

    Hey ... Now all the Hard Drive are of 2015 model ... It's August 2016 ... Let me know if the new model Hard drive will be launched soon enough or not .... As per my analysis every 1 year the market shift the price .....

  5. ryan
    August 3, 2016 at 6:16 am

    How old is this article? It's in serious need of an update. "[hard drives]...cap out at 4TB per drive." Um. No. "consumer-level SSDs rarely exceed 512GB." Again, false.

    • Anon Y. Mouse
      November 12, 2016 at 9:14 am

      Right under the title.
      "March 23, 2015"

  6. Byron Gordon
    July 24, 2016 at 4:25 pm

    Joel,

    I don't know if you're still reading the comments from this post of yours but if you are, I greatly appreciate your feedback. First, thank you for a very informative read. I wanted to learn and understand better the difference between a SSD and a HDD. Do you have any recommendations for ready-made PCs that have a SSD installed in it? I can't seem to find very many at all. I would have thought Dell, one of the kings of PC makers would have a line-up of PCs with SSDs in them but they don't. All I could I identify is one! And that's their XPS 8900 special edition. And it is expensive, around $1,500. But I can't find any other recommended PC with a SSD. Can you recommend any?

  7. vishal saraswat
    June 5, 2016 at 10:55 am

    very informative indeed and that additional hyperlinks also helped in increasing my understanding.
    thanks alot

    • Joel Lee
      June 7, 2016 at 4:22 pm

      You're welcome, vishal. Glad you found it useful. :)

  8. Hmm
    June 4, 2016 at 6:01 am

    I would like to see what is in store in the future. For example, several years ago I spent a lot on a new system and about a year later, UEFI was the gold standard which really ticked me off. At that time SATA 6 was sharing bandwidth with the video slot, part of Asus mobo's. I believe that is no longer the case.

    As we are also seeing USB 3.1 replace USB 3.0, it would nice to have a better idea of what is planned for the next year or two in terms of PC peripheral advancements.

  9. Alpesh
    April 1, 2016 at 1:02 pm

    Good article

    • Joel Lee
      April 12, 2016 at 10:42 pm

      Thanks Alpesh! Appreciate it. :)

  10. Papillon
    February 5, 2016 at 11:44 pm

    One thing that doesn''t often gets accounted with is the power consumption per TB. This is a advantage to SSD's, however at a price tag (SSD tend to cast approx 250 per TB).

    Now comes the part not everyone sees. 3.5 inch spindle drives (@5400 rpm) often use approx 5 - 7 W idle. The 2.5 inch drives however approx 0.7 - 1.4 W. I ended up with building a NAS based on 2.5 inch (1.5 TB M9T) drivers. Per GB a little more, but keeping in mind that every W continous usage is apprx 1.8 EUR a year. With 4 TB I get approx 1.5 W per TB (approx 30 EUR per TB) and with 2.5 inch drives I get approx 0.5 W per TB (approx 37 EUR per TB). The price difference between these drives per TB justify the power savings (ROI of 3.7 years).

    Quite a mathmetic thing.. but to me this is true.

  11. Kelsey Tidwell
    April 10, 2015 at 11:50 pm

    Line n above, I was thinking there was another form factor, and there is at least one.
    Many Chromebooks use the NGFF, or Next Generation Form Factor, which measures 22x42x1mm (referred to as "2242").

    • Joel Lee
      April 12, 2015 at 1:30 am

      Ah, so M.2 and NGFF are both the same thing? Interesting!

  12. Cool Penguin
    March 29, 2015 at 8:45 pm

    Seagate (at least) makes an 8TB HDD.

    I also have to give props here to Silicon Power external drives. I had bought 5 or 6 external drives from big name manufacturers with good reputations and every single one of them failed within 2 years. I finally decided to do some research into drives intended to be shockproof, not because I abuse drives, but because I figured they'd protect the delicate parts that tend to fail.

    I went to amazon and started to read reviews and found one that said to search "silicon power a80 torture test" on youtube. I did, and no other reviews were necessary. I bought one right away, and it is now 3 years old.

  13. A41202813GMAIL
    March 24, 2015 at 6:57 pm

    No Crap SSDs - Only Storage With Moving Parts, Period.

    Internal SATA 3.5 HDD - The Bigger The Better.

    Cheers.

    • Joel Lee
      April 12, 2015 at 1:31 am

      I'm guessing you don't think that the increased speed warrants the move to flash memory? Would you consider a mix-and-match approach with HDDs for important data and SSDs for OS/programs?

    • A41202813GMAIL
      April 12, 2015 at 1:51 am

      I Have Never Used SSDs.

      How Different Is Their Technology From USB Flash Drives ?

      Some Of The Files In USB Flash Drives Become Easily Corrupted.

      For Me, No Storage Without Moving Parts, Period.

      Thank You For Responding.

      • God
        March 1, 2016 at 6:49 pm

        ssds are ridiculously fast compared to slow older hard drives. The problem is that they are too pricey. When I had my 240gig ssd in my gaming desktop it would boot pc games almost immediately and loading times were almost non-existent. While on my 7200rpm hard drive loading times on games varied from 30 seconds to a minute.

        • A41202813GMAIL ..
          March 2, 2016 at 8:40 am

          "Power Is Nothing Without Control" Is A Well Known Slogan For Some Tech Company.

          I Will Not Trade Reliability For Speed, Ever.

          I Would Not Mind Pricey Reliable Devices.

          Companies Should Pay Customers To Use Their Crap, Not The Other Way Around, Period.

          Cheers.

  14. Rick M
    March 24, 2015 at 3:41 am

    Your article is referring to consumer drives correct? On the enterprise side we have 6TB SATA drives and 1.92TB cMLC SSD drives available.. These are expensive little guys listing at over $14K each list price but guaranteed for 5 years. Using de duplication technology and compaction we can get the cost down to about $1.52 per GB. Very soon you'll see 3.84TB SSD but I have no idea who will be able to afford them.

    • Joel Lee
      April 12, 2015 at 1:29 am

      Yes, we try to focus on the consumer side unless explicitly stated otherwise. But you're right, there are a lot of HUGE HDDs and SSDs out there that can cost more than cars!

  15. n
    March 23, 2015 at 2:23 pm

    You say that 'there are only two choices' for drive sizes, however my Dell laptop has a 1.8" drive with ZIF connector inside. I know that it isn't very common but this laptop is not very old (came with Windows 7) and so maybe the article should be updated to reflect there is a rarer option out there.

    • Joel Lee
      April 12, 2015 at 1:28 am

      Wow, I've never seen a 1.8" ZIF in the wild. I wonder how those are doing in terms of market growth? Would be interesting to see some stats since, as you mentioned, they are pretty rare.

  16. Jon Green
    March 23, 2015 at 12:54 pm

    No mention of hybrid drives: a combination of HDD and SSD that delivers most of the SSD speed at HDD capacities, and near-HDD pricing.

    Also, no mention of one major win for SSDs over HDDs: near-invulnerability to physical shock, which can annihilate spinning HDDs (and potentially damage ones that aren't even spinning).

    Finally, external drives aren't necessarily just USB-connected. Thunderbolt and (to an extent) ePCIe are also used. And watch out for the new USB-C devices, which are not connector-compatible with existing USB.

    • likefunbuntot
      March 23, 2015 at 5:06 pm

      The benefit of a hybrid drive is pretty minimal for the cost. They made a certain amount of sense when an 80GB SSD cost more than a decent laptop, but 10% improvement in access time (if you're lucky ) over any old 7200rpm drive is fairly dubious otherwise. Since relatively high capacity 480GB drives can now be found for $.40/GB, they're really more of a curiosity these days than a viable product.

    • Joel Lee
      April 12, 2015 at 1:26 am

      Regarding hybrid drives, I considered including them but figured that their era would soon be coming to an end (look to likefunbutnot for reasons). But you're right, I should've mentioned them off-hand, at least.

      Notes on Thunderbolt, ePCIe, and USB-C were good, thanks for bringing them up!

  17. likefunbutnot
    March 23, 2015 at 12:40 pm

    You may also have the option to select a different disk interface. Small form factor desktop boards and business-type notebook computers frequently support tiny mSATA solid state drives while new high-end desktops and business laptops may offer the option of M.2 drives.

    mSATA is technically just a very small SATA drive, but having one opens the option of using existing drive bays for slower high-capacity drives. On a laptop, an mSATA drive also represents a small savings in weight and an improvement in battery efficiency vs. a traditional magnetic disk.

    m.2 is a direct link to the PCI Express bus, meaning that it is a disk that has a straight connection to your CPU. m.2 drives, while not capable of accessing data more quickly than other SSDs, do tend to transfer data much more quickly. High end M.2 drives from Samsung and Plextor are capable of moving around 900MB/sec of data in real-world data transfer tests vs. 300 - 400MB/sec for most SSDs.

    Finally, as an IT guy: External drives are, in almost all cases, just internal drives with an adapter board to turn a SATA connection into USB. USB, even USB Superspeed ("USB 3.0") will never provide end users the data transfer rates that the protocol theoretically offers. Your external drive will always be slower on USB than it will on some other external interface like External SATA, Thunderbolt or even in some cases Firewire. If you have the option to use something besides USB to plug in a drive and you're at all concerned about speed, the other thing is probably better. Also, external drives are not indestructible. For some reason, there's a common perception that external drive "backup drive" and "backup drive" = does not fail. This causes headaches for the techies trying to help end users far more often than anyone else would suspect.

    • Joel Lee
      April 12, 2015 at 1:24 am

      Learned some new stuff here, so thanks a lot for sharing. Really appreciate it!

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