Buying an external hard drive for your Mac is not all that different from buying one for your Windows PC, except for one very important complication: The latest Mac laptops only come with Thunderbolt 3 ports, but the arrival of Thunderbolt 3-equipped drives has been a trickle, rather than a flood. Most of the current models that use the Apple-friendly interface are designed for photographers and video editors who need to store mountains of footage and access it very quickly. As a result, they are typically external SSDs, or multidrive RAID arrays, which means they’re also very expensive.
So what’s a Mac user to do who just wants to back up his or her files using Time Machine, or stash a large video collection? Read on as we solve this and all of your other Mac external-storage quandaries. (Spoiler: A Thunderbolt 3 drive isn’t your only option; far from it.)
Before we get to Thunderbolt 3, we need to address a basic building block of hard drives that has always affected compatibility, and probably always will: the file system.
An external drive’s file system is the most important factor that determines whether or not it’s readable by Macs, PCs, or both. With the release of the macOS High Sierra operating system, Cupertino ditched its venerable Mac OS Extended file system, commonly abbreviated as HFS , and switched to an entirely new file system. It’s simply called the Apple File System (APFS), and it’s the first format to be used across both Macs and iOS devices.
solid-state or spinning disk. Each has its advantages and disadvantages, and—unlike the file system—the type you buy is the type you’re stuck with for the life of the drive.
A solid-state drive (SSD) offers quick access to your data because it stores your bits in a type of flash memory rather than on spinning platters. SSDs are often smaller and lighter than spinning external drives, as well, which is also thanks to the lack of moving parts. Their small size means they can often fit into a jacket or pants pocket, which makes them a better choice if you’re looking for a portable external drive that you’ll be carrying with you frequently. (See our overall picks for favorite external SSDs.)
4K footage and gamers or movie buffs who have large libraries of multi-gigabyte titles, an external RAID array made up of multiple platter-based drives is worth considering, since it combines the near-speed of an SSD with the gargantuan possible capacities of spinning drives. An array contains two or more drives that all work together to increase throughput, or guard your precious files against corruption via drive redundancy if one of the drives fail. (Or both; it depends on how the array is set up.) The result is that you can get SSD-like speeds, with throughput of more than 400MBps, and capacities that top out close to 50TB. You’ll pay handsomely, of course—some Mac-specific arrays cost thousands of dollars.
On the other hand, if you’re looking to buy an external drive mainly to back up your files (which you should definitely do) and it will rarely leave your home office, an inexpensive spinning drive will work just fine. These come in both portable and “desktop” versions.
The portables are obviously smaller, and are based on the kinds of 2.5-inch platter drives used in laptops. Desktop-style external hard drives are larger, are based on the beefier and more capacious 3.5-inch drives used in full-size desktop PCs, and require their own AC power source. Portable drives don’t have a power plug; they get the juice they need to run through their data interface.
Does Thunderbolt 3 Matter, or Will USB-C Do?
So, to recap: Faster, smaller (both physically and in terms of gigabytes) solid-state drives come at a premium, while spinning drives offer a much better value while sacrificing speed. But what happens when you throw yet another variable into the mix: the connection between your drive and your Mac? As you might have guessed, the answer is more tradeoffs.
Every current Mac laptop comes with oval-shaped USB Type-C ports that support Thunderbolt 3, but other than a headphone jack, they are the only connectivity options available, which means you’ll need an adapter to plug in any device that doesn’t have a USB Type-C cable. The silver lining is that Thunderbolt 3 via USB Type-C supports a blazing maximum potential throughput of 40Gbps, double the speed of the old Thunderbolt 2 standard and many times the 5GBps that USB 3.0 offers. (See our deep dive on the differences between Thunderbolt 3 versus USB-C.)
best external SSDs for more discussion of this.)
See our guide to using Time Machine for backups.)
The first time you plug in an external drive, Time Machine will ask if you want to use it as a backup drive. While you can customize backup options in System Preferences, such as asking Time Machine to exclude certain folders, there’s no action required on your part if you’re happy with the default settings. The next time you plug in your drive, Time Machine will automatically set to work creating a backup.
our favorite rugged drives.)
Finally, you might want to consider how the drive will look when it’s plugged into your Mac. Some drives come in a variety of colors. Many others feature copious amounts of aluminum and industrial-chic styling to match the design cues of your MacBook or iMac.