5 Types of External Drives for Your Mac

Upgrading a Mac with an external drive is easy

Your Mac came from Apple equipped with at least one internal drive. Depending on the Mac model you have, it could be a 3.5-inch desktop platter hard drive, a 2.5-inch laptop hard drive, or a 2.5-inch SSD (Solid State Drive). Some Macs, including specific models of the iMac, Mac mini, and Mac Pro, were offered with an additional internal storage device, or at least with room for the end user to add more drives.

But when it comes right down to it, the 2006-2012 Mac Pros are the only Intel-based Mac models that have easily user upgradeable drive space.

If your Mac isn't a Mac Pro, it's likely that if you need more storage space, you're going to go with an external drive.

External Drive Types for the Mac

External drives can be categorized by the type of drives the external enclosures contain, as well as the interface type that is used to connect the external enclosure to a Mac.

This guide concentrates on Macs from 2006 on, which means that external storage options should be able to work with FireWire 400 and 800 ports, USB 2 and USB 3.1 ports, Thunderbolt, Thunderbolt 2, and Thunderbolt 3, the newest of the ports.

Now, any single enclosure doesn't need to contain all of these port types. But if you're buying a new external enclosure, it should at least have a USB 3.1 port, to ensure compatibility with newer Macs (even if you don't own one yet). USB 3.1 is backward compatible with USB 2, so it should be usable on older Macs as well.

When we say that a USB 3 drive is usable on an older Mac, we mean just that: usable. It is by no means optimal. If you plan to use your older Mac for the foreseeable future, make sure that the external drive supports one of your faster connection types, specifically FireWire 800 or FireWire 400; both are faster than a USB 2 port.

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Increase Storage With an External Drive for Your Mac

Apple superdrive external hard drive.
Evan-Amos/Wikimedia Commons/Public Domain

External drives are available for many purposes. They can be used for backup, primary data storage, secondary storage, media library, and even as a startup drive. They can also be easily moved to another compatible Mac, if necessary. This versatility makes external drives the popular choice for upgrading storage.

External drives are available in many styles, including single-drive enclosures, multi-drive enclosures, prebuilt enclosures, bus-powered enclosures (no external power supply needed) and DIY enclosures. And we haven't even gotten to the interface options yet.

Before you purchase an external drive, use this guide to learn more about the various types of external drives and how they connect to a Mac.

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Build Your Own External Hard Drive

Bus powered external drive.

Karen/Flickr/CC BY 2.0

Taking a DIY approach and building your own external drive for your Mac allows you to pick the enclosure you like, with the interface you need, and install the type of drive you want. And in some cases, you can do this less expensively than buying a pre-built, off-the-shelf model.

Of course, you have to spend some time looking for the best enclosure for the project, as well as decide which drive you want and where to purchase it, so in the long run, it takes more time than just buying a ready-to-run solution. But, saving money and building it yourself; what’s not to like?

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Where to Buy External Drive Enclosures

OWC ThunderBay 4 mini.


There are a few sites and manufacturers you can always check when in the market for a ready-to-go solution. That's where you buy the external drive enclosure, the drive, and any necessary cables, already assembled.

The advantage is that you end up with a quick solution to your storage expansion needs. Simply remove the drive from the shipping box, plug it into power and your Mac, flip the switch, format the drive, and you're ready to go.

  • Buffalo Technology has a line of desktop drives called DriveStation that are often used for backup solutions. Many of the models support multiple drives as well as data encryption. Buffalo Technology's portable lineup includes USB 3, and Thunderbolt models. The company also offers NAS (network attached storage) models for a complete network solution to your expansion needs.
  • G-Technology has a wide range of products to choose from, including its popular G Drive series of desktop drives, available in single and multi-drive configurations. G-Technology's portable lineup is also impressive and includes multi-drive portable options. Many of the enclosures make use of solid-state drives (SSDs) to really help boost your Mac's performance. You'll also find a good selection of RAID systems, including docking stations that let you replace a drive without having to power off the storage system.
  • LaCie offers external drives for just about any interface you want to use, including USB-C, USB 3.1, Thunderbolt, and NAS. LaCie has external drives for mobile use; simply pick one up and go. There are also drives available for desktop use or creating RAID arrays. LaCie drives are available for use with 3 1/2 inch hard drives, or smaller 2 1/2 inch laptop drives and SSDs.
  • Other World Computing may have the widest selection of desktop, portable, and RAID-based external storage solutions available specifically for the Mac. OWC also offers enclosures with a wide range of interfaces, including many that offer multiple ports so you can use the enclosure today with your 2008 MacBook Pro and its FireWire ports, and later use it with USB 3.1 gen 2 when you upgrade to a new Mac.
  • Promise Technology specializes in high-performance storage systems. Its Mac-compatible products include Thunderbolt-based single and multi-drive enclosures. Promise Technology also has a selection of Fibre Channel and eSATA-based enclosures, primarily for use on the Mac Pro with a PCIe expansion card that includes the necessary interface types.
  • Seagate has quite a few portable and desktop storage solutions for Mac users. It also offers NAS systems for home and business use. You will find single and dual drive models, as well as your choice of USB 2, USB 3, and Thunderbolt enclosures.
  • Western Digital offers external drive solutions for desktop and portable Macs. WD also makes NAS drives, which it calls Personal Cloud drives, that are Time Machine compatible, a nice feature if you're looking for backup solutions for multiple Macs.
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Your Home Folder Doesn't Have to Be on Your Startup Drive

Moving the home folder on your Mac.

Coyote Moon, Inc.

Now that you have an external drive, you may want to consider moving your home folder to that drive, to free up space on your Mac's startup drive.

This is especially true if your Mac has an SSD for a startup drive. Moving your user data will provide a lot of free space on the SSD. But this only works if your Mac is always connected to the external drive. If you tuck your Mac under your arm and hit the road without the external drive, you'll be leaving all your user data behind.

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Using macOS Disk Utility

Disk Utility Information.

Coyote Moon, Inc.

When you purchase a new external drive, chances are you’re going to need to use Disk Utility to format or partition the drive to meet your needs. This guide provides details for using Disk Utility.