Self storage for your computer - Choosing an External Hard Drive

Think of an external hard drive as a self-storage unit for your computer. Although you aren’t renting it by the month, the principles to buy a hard drive are the same; you pay for space, convenience, features and security.

So when it comes time to add or upgrade an external hard drive (EHD), how do you make a smart choice?

First of all, know that it’s hard to make a bad choice. The first hard drive was shipped by IBM in 1956. Which is to say that the technology is about as mature as it can get. It also means that the cost per gigabyte of storage on a hard drive is a bargain compared to other media and online services, because it’s not cutting edge stuff.

On top of that, there are only 3 hard drive manufacturers left in the world: Toshiba, Western Digital (which owns HGST), and Seagate (which owns LaCie and others). That’s down from about 200 manufacturers at the industry’s peak. So, out of the box (so to speak) the chances of getting a reliable hard drive is really good. They know their stuff and they’ve been doing it for a long, long time.

So what are you buying?

When we talk about external hard drives, we’re really talking about the actual hard drive mechanism enclosed in a casing that offers one or more cable connections and activity lights that tell us when something is happening. When one of the hard drive manufacturers or a third party like Buffalo or G-Tech makes an external drive, they are buying one of the available hard drives and putting it in a casing of their own design. They can choose what kind of connection to include - USB 2.0 or 3.0, Firewire, Thunderbolt, eSata, or even WiFi. They can waterproof or cushion the drive. Make it big or small. They usually install some software for disk maintenance and file management, and may include their own backup software as an option. They may format the drive for Mac or PC or create automatic setup software for the user to choose.

So at the end of the day, you are just buying a storage space that has some extra features for performance, convenience and style.

Let’s look at those more closely.


When calculating the size of a hard drive, keep in mind that you want to have at least 10% of the volume size free of data for the drive to work efficiently. If you are doing image editing on the drive, 25% is better as many apps store temporary versions and backups of the file you are editing. Like our storage unit, if the space is completely filled with stuff, we have to move some out of the way to get at the box we want. It takes more time and effort for us and for the computer.

It’s a good idea to buy at least double the space that you think you need, but be aware that you pay a premium for whatever the largest sizes are in the market. 3 years ago, 2TB drives were only available at astronomical prices. Today you can find great deals on them because 4TB and 6TB drives are on the shelves.

If the EHD is to expand your internal storage, remember that it needs to be backed up somewhere. Every hard drive will eventually fail, so it’s essential that you have all data in at least 2 places. Best practices for backups actually specify 3 places, with at least one of them offsite. This is the voice of experience. To that end, you might want to buy a 1TB drive for media and a 2TB drive to back it up along with your internal hard drive.


Unsurprisingly, you pay for faster performance in the form of connection and hard drive speeds, so choosing an EHD that suits your needs is important. Thunderbolt and eSata drives are more pricy because of the faster transfer times. When copying a large database, that can be a lifesaver if the computer supports those connections. At the other end, USB 2.0 is an older, slower connection technology that can be included on a cheaper price point EHD and works with pretty much any computer.

Here’s how that plays out.

If you are using the drive for regular copying of large files, folders or libraries, then it’s worth paying for Thunderbolt, Firewire or USB 3.0. Also if you are working directly from the EHD in some application like Lightroom, Photos or Photoshop that pushes a lot of data and also benefits from the faster connection.

On the other hand, if your drive is just a backup or transfer drive that is plugged in every few days and doesn’t see a lot of traffic, you can save some money with a slower USB 2.0 drive.

Another facet of the overall experience is the speed of the hard drive itself. A hard drive is like a CD player in that there is a platter holding the data and an arm hovering about a hair’s width above the surface that reads the data. Standard hard drives spin the platter at 5400 rpm. The faster drives spin at 7200 rpm which allows more data to be read or written to the disk in the same amount of time. Editing large image files and video benefits from the faster read/write speeds.


Some drives offer multiple connections. A nice combination for active use is a drive outfitted with both Thunderbolt and USB 3.0 connections. LaCie and Buffalo drives are 2 examples. Thunderbolt is very fast and standard on all recent Macs. Using a Thunderbolt to Firewire adapter you can also access the Firewire output on older Macs. USB 3.0 is standard on PC’s and is backwardly compatible to the slower USB 2.0.

A cool new option is WiFi enabled drives like the Buffalo MiniStation Air or Sandisk Media Drive. These offer both USB and WiFi connections to allow for transfers from mobile devices as well as computers. They can also stream media over their WiFi connection so they are handy on long car trips if the kids all want to watch a different movie on their iPads.


External Hard Drives come in all shapes and sizes, from ultra portable to ultra tough. For instance, LaCie makes a series of Rugged drives that have plastic bumpers to protect them from drops in hard use. G-Tech has drive casings that accept swappable drive modules so you can upgrade and add modules without buying a whole new drive mechanism. There are designer drives, ultra thin drives, decorator drives, and RAID drives with 2 or more hard drives in the enclosure.

Also, there are 2 sizes of hard drives that an EHD designer can use.

The 2.5” drives used in the smaller, portable EHD’s are the same hard drives used in laptops and allow for thin, lightweight drives that are not much bigger than a smartphone. They are great for occasional backup, transferring data, and offloading media from a main hard drive, and traveling. They draw power from the computer connection so they can be used anywhere.

The larger 3.5” drives are designed for desktop computers and servers, are available in larger capacities than the 2.5” drives and are happy running 24/7. Because the casing is bigger, there is room for multiple connection ports, security locks, and cooling fans. These drives also require AC Power unlike most portable drives. But in exchange for portability, the bigger drives are made for continuous daily use, faster performance and better reliability.

Picking your EHD storage unit

Okay, so what does it all mean?

As I said at the beginning, it’s hard to make a bad choice these days. Hard drive technology is well understood and the 3 remaining hard drive manufacturers have succeeded because they know what they’re doing and produce good products that they stand behind.

So, in the end, it’s about those extras when we chose our self-storage unit. Did we want to be close to the entry? Good lighting? Climate control? Size of unit?

Ultimately, if you can get all the data onto the drive and have some extra space to work, then it doesn’t matter what EHD you buy, but here are some guidelines that may help guide your choices:

  • Compact portable 2.5” drives - These are small and handy as extra drives for copying data and transporting. Good choice to archive data for offsite storage. Usually include a USB(2.0 or 3.0) connection only. Can run hot if left plugged in continuously. Often discounted. PC formatted drives are easily reformatted to suit Mac or both operating systems.

  • Premium portable 2.5” drives - Enthusiast and professional level usage. More substantial enclosures. Faster connections - Thunderbolt, USB 3.0, Firewire. May offer multiple connections (Thunderbolt & USB 3.0). Can be left connected without overheating. May have optional AC power.

  • Desktop 3.5” drives - Designed for continuous use as supplement to internal drive or active backup. Larger capacity, faster connections and generally faster performance. May offer additional features like built in USB hub and duplicate connections to daisy chain drives. Requires AC power.

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UncategorizedPaul Einarsen